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core/num/
f32.rs

1//! Constants for the `f32` single-precision floating point type.
2//!
3//! *[See also the `f32` primitive type][f32].*
4//!
5//! Mathematically significant numbers are provided in the `consts` sub-module.
6//!
7//! For the constants defined directly in this module
8//! (as distinct from those defined in the `consts` sub-module),
9//! new code should instead use the associated constants
10//! defined directly on the `f32` type.
11
12#![stable(feature = "rust1", since = "1.0.0")]
13
14use crate::convert::{FloatToFloat, FloatToInt};
15use crate::num::FpCategory;
16use crate::panic::const_assert;
17use crate::{cfg_select, intrinsics, mem};
18
19/// The radix or base of the internal representation of `f32`.
20/// Use [`f32::RADIX`] instead.
21///
22/// # Examples
23///
24/// ```rust
25/// // deprecated way
26/// # #[allow(deprecated)]
27/// let r = std::f32::RADIX;
28///
29/// // intended way
30/// let r = f32::RADIX;
31/// ```
32#[stable(feature = "rust1", since = "1.0.0")]
33#[deprecated(since = "1.99.0", note = "replaced by the `RADIX` associated constant on `f32`")]
34#[rustc_diagnostic_item = "f32_legacy_const_radix"]
35pub const RADIX: u32 = f32::RADIX;
36
37/// Number of significant digits in base 2.
38/// Use [`f32::MANTISSA_DIGITS`] instead.
39///
40/// # Examples
41///
42/// ```rust
43/// // deprecated way
44/// # #[allow(deprecated)]
45/// let d = std::f32::MANTISSA_DIGITS;
46///
47/// // intended way
48/// let d = f32::MANTISSA_DIGITS;
49/// ```
50#[stable(feature = "rust1", since = "1.0.0")]
51#[deprecated(
52    since = "1.99.0",
53    note = "replaced by the `MANTISSA_DIGITS` associated constant on `f32`"
54)]
55#[rustc_diagnostic_item = "f32_legacy_const_mantissa_dig"]
56pub const MANTISSA_DIGITS: u32 = f32::MANTISSA_DIGITS;
57
58/// Approximate number of significant digits in base 10.
59/// Use [`f32::DIGITS`] instead.
60///
61/// # Examples
62///
63/// ```rust
64/// // deprecated way
65/// # #[allow(deprecated)]
66/// let d = std::f32::DIGITS;
67///
68/// // intended way
69/// let d = f32::DIGITS;
70/// ```
71#[stable(feature = "rust1", since = "1.0.0")]
72#[deprecated(since = "1.99.0", note = "replaced by the `DIGITS` associated constant on `f32`")]
73#[rustc_diagnostic_item = "f32_legacy_const_digits"]
74pub const DIGITS: u32 = f32::DIGITS;
75
76/// [Machine epsilon] value for `f32`.
77/// Use [`f32::EPSILON`] instead.
78///
79/// This is the difference between `1.0` and the next larger representable number.
80///
81/// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
82///
83/// # Examples
84///
85/// ```rust
86/// // deprecated way
87/// # #[allow(deprecated)]
88/// let e = std::f32::EPSILON;
89///
90/// // intended way
91/// let e = f32::EPSILON;
92/// ```
93#[stable(feature = "rust1", since = "1.0.0")]
94#[deprecated(since = "1.99.0", note = "replaced by the `EPSILON` associated constant on `f32`")]
95#[rustc_diagnostic_item = "f32_legacy_const_epsilon"]
96pub const EPSILON: f32 = f32::EPSILON;
97
98/// Smallest finite `f32` value.
99/// Use [`f32::MIN`] instead.
100///
101/// # Examples
102///
103/// ```rust
104/// // deprecated way
105/// # #[allow(deprecated)]
106/// let min = std::f32::MIN;
107///
108/// // intended way
109/// let min = f32::MIN;
110/// ```
111#[stable(feature = "rust1", since = "1.0.0")]
112#[deprecated(since = "1.99.0", note = "replaced by the `MIN` associated constant on `f32`")]
113#[rustc_diagnostic_item = "f32_legacy_const_min"]
114pub const MIN: f32 = f32::MIN;
115
116/// Smallest positive normal `f32` value.
117/// Use [`f32::MIN_POSITIVE`] instead.
118///
119/// # Examples
120///
121/// ```rust
122/// // deprecated way
123/// # #[allow(deprecated)]
124/// let min = std::f32::MIN_POSITIVE;
125///
126/// // intended way
127/// let min = f32::MIN_POSITIVE;
128/// ```
129#[stable(feature = "rust1", since = "1.0.0")]
130#[deprecated(
131    since = "1.99.0",
132    note = "replaced by the `MIN_POSITIVE` associated constant on `f32`"
133)]
134#[rustc_diagnostic_item = "f32_legacy_const_min_positive"]
135pub const MIN_POSITIVE: f32 = f32::MIN_POSITIVE;
136
137/// Largest finite `f32` value.
138/// Use [`f32::MAX`] instead.
139///
140/// # Examples
141///
142/// ```rust
143/// // deprecated way
144/// # #[allow(deprecated)]
145/// let max = std::f32::MAX;
146///
147/// // intended way
148/// let max = f32::MAX;
149/// ```
150#[stable(feature = "rust1", since = "1.0.0")]
151#[deprecated(since = "1.99.0", note = "replaced by the `MAX` associated constant on `f32`")]
152#[rustc_diagnostic_item = "f32_legacy_const_max"]
153pub const MAX: f32 = f32::MAX;
154
155/// One greater than the minimum possible normal power of 2 exponent.
156/// Use [`f32::MIN_EXP`] instead.
157///
158/// # Examples
159///
160/// ```rust
161/// // deprecated way
162/// # #[allow(deprecated)]
163/// let min = std::f32::MIN_EXP;
164///
165/// // intended way
166/// let min = f32::MIN_EXP;
167/// ```
168#[stable(feature = "rust1", since = "1.0.0")]
169#[deprecated(since = "1.99.0", note = "replaced by the `MIN_EXP` associated constant on `f32`")]
170#[rustc_diagnostic_item = "f32_legacy_const_min_exp"]
171pub const MIN_EXP: i32 = f32::MIN_EXP;
172
173/// Maximum possible power of 2 exponent.
174/// Use [`f32::MAX_EXP`] instead.
175///
176/// # Examples
177///
178/// ```rust
179/// // deprecated way
180/// # #[allow(deprecated)]
181/// let max = std::f32::MAX_EXP;
182///
183/// // intended way
184/// let max = f32::MAX_EXP;
185/// ```
186#[stable(feature = "rust1", since = "1.0.0")]
187#[deprecated(since = "1.99.0", note = "replaced by the `MAX_EXP` associated constant on `f32`")]
188#[rustc_diagnostic_item = "f32_legacy_const_max_exp"]
189pub const MAX_EXP: i32 = f32::MAX_EXP;
190
191/// Minimum possible normal power of 10 exponent.
192/// Use [`f32::MIN_10_EXP`] instead.
193///
194/// # Examples
195///
196/// ```rust
197/// // deprecated way
198/// # #[allow(deprecated)]
199/// let min = std::f32::MIN_10_EXP;
200///
201/// // intended way
202/// let min = f32::MIN_10_EXP;
203/// ```
204#[stable(feature = "rust1", since = "1.0.0")]
205#[deprecated(since = "1.99.0", note = "replaced by the `MIN_10_EXP` associated constant on `f32`")]
206#[rustc_diagnostic_item = "f32_legacy_const_min_10_exp"]
207pub const MIN_10_EXP: i32 = f32::MIN_10_EXP;
208
209/// Maximum possible power of 10 exponent.
210/// Use [`f32::MAX_10_EXP`] instead.
211///
212/// # Examples
213///
214/// ```rust
215/// // deprecated way
216/// # #[allow(deprecated)]
217/// let max = std::f32::MAX_10_EXP;
218///
219/// // intended way
220/// let max = f32::MAX_10_EXP;
221/// ```
222#[stable(feature = "rust1", since = "1.0.0")]
223#[deprecated(since = "1.99.0", note = "replaced by the `MAX_10_EXP` associated constant on `f32`")]
224#[rustc_diagnostic_item = "f32_legacy_const_max_10_exp"]
225pub const MAX_10_EXP: i32 = f32::MAX_10_EXP;
226
227/// Not a Number (NaN).
228/// Use [`f32::NAN`] instead.
229///
230/// # Examples
231///
232/// ```rust
233/// // deprecated way
234/// # #[allow(deprecated)]
235/// let nan = std::f32::NAN;
236///
237/// // intended way
238/// let nan = f32::NAN;
239/// ```
240#[stable(feature = "rust1", since = "1.0.0")]
241#[deprecated(since = "1.99.0", note = "replaced by the `NAN` associated constant on `f32`")]
242#[rustc_diagnostic_item = "f32_legacy_const_nan"]
243pub const NAN: f32 = f32::NAN;
244
245/// Infinity (∞).
246/// Use [`f32::INFINITY`] instead.
247///
248/// # Examples
249///
250/// ```rust
251/// // deprecated way
252/// # #[allow(deprecated)]
253/// let inf = std::f32::INFINITY;
254///
255/// // intended way
256/// let inf = f32::INFINITY;
257/// ```
258#[stable(feature = "rust1", since = "1.0.0")]
259#[deprecated(since = "1.99.0", note = "replaced by the `INFINITY` associated constant on `f32`")]
260#[rustc_diagnostic_item = "f32_legacy_const_infinity"]
261pub const INFINITY: f32 = f32::INFINITY;
262
263/// Negative infinity (−∞).
264/// Use [`f32::NEG_INFINITY`] instead.
265///
266/// # Examples
267///
268/// ```rust
269/// // deprecated way
270/// # #[allow(deprecated)]
271/// let ninf = std::f32::NEG_INFINITY;
272///
273/// // intended way
274/// let ninf = f32::NEG_INFINITY;
275/// ```
276#[stable(feature = "rust1", since = "1.0.0")]
277#[deprecated(
278    since = "1.99.0",
279    note = "replaced by the `NEG_INFINITY` associated constant on `f32`"
280)]
281#[rustc_diagnostic_item = "f32_legacy_const_neg_infinity"]
282pub const NEG_INFINITY: f32 = f32::NEG_INFINITY;
283
284/// Basic mathematical constants.
285#[stable(feature = "rust1", since = "1.0.0")]
286#[rustc_diagnostic_item = "f32_consts_mod"]
287pub mod consts {
288    // FIXME: replace with mathematical constants from cmath.
289
290    /// Archimedes' constant (π)
291    #[stable(feature = "rust1", since = "1.0.0")]
292    pub const PI: f32 = 3.14159265358979323846264338327950288_f32;
293
294    /// The full circle constant (τ)
295    ///
296    /// Equal to 2π.
297    #[stable(feature = "tau_constant", since = "1.47.0")]
298    pub const TAU: f32 = 6.28318530717958647692528676655900577_f32;
299
300    /// The golden ratio (φ)
301    #[doc(alias = "phi")]
302    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
303    pub const GOLDEN_RATIO: f32 = 1.618033988749894848204586834365638118_f32;
304
305    /// The Euler-Mascheroni constant (γ)
306    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
307    pub const EULER_GAMMA: f32 = 0.577215664901532860606512090082402431_f32;
308
309    /// π/2
310    #[stable(feature = "rust1", since = "1.0.0")]
311    pub const FRAC_PI_2: f32 = 1.57079632679489661923132169163975144_f32;
312
313    /// π/3
314    #[stable(feature = "rust1", since = "1.0.0")]
315    pub const FRAC_PI_3: f32 = 1.04719755119659774615421446109316763_f32;
316
317    /// π/4
318    #[stable(feature = "rust1", since = "1.0.0")]
319    pub const FRAC_PI_4: f32 = 0.785398163397448309615660845819875721_f32;
320
321    /// π/6
322    #[stable(feature = "rust1", since = "1.0.0")]
323    pub const FRAC_PI_6: f32 = 0.52359877559829887307710723054658381_f32;
324
325    /// π/8
326    #[stable(feature = "rust1", since = "1.0.0")]
327    pub const FRAC_PI_8: f32 = 0.39269908169872415480783042290993786_f32;
328
329    /// 1/π
330    #[stable(feature = "rust1", since = "1.0.0")]
331    pub const FRAC_1_PI: f32 = 0.318309886183790671537767526745028724_f32;
332
333    /// 1/sqrt(π)
334    #[unstable(feature = "more_float_constants", issue = "146939")]
335    pub const FRAC_1_SQRT_PI: f32 = 0.564189583547756286948079451560772586_f32;
336
337    /// 1/sqrt(2π)
338    #[doc(alias = "FRAC_1_SQRT_TAU")]
339    #[unstable(feature = "more_float_constants", issue = "146939")]
340    pub const FRAC_1_SQRT_2PI: f32 = 0.398942280401432677939946059934381868_f32;
341
342    /// 2/π
343    #[stable(feature = "rust1", since = "1.0.0")]
344    pub const FRAC_2_PI: f32 = 0.636619772367581343075535053490057448_f32;
345
346    /// 2/sqrt(π)
347    #[stable(feature = "rust1", since = "1.0.0")]
348    pub const FRAC_2_SQRT_PI: f32 = 1.12837916709551257389615890312154517_f32;
349
350    /// sqrt(2)
351    #[stable(feature = "rust1", since = "1.0.0")]
352    pub const SQRT_2: f32 = 1.41421356237309504880168872420969808_f32;
353
354    /// 1/sqrt(2)
355    #[stable(feature = "rust1", since = "1.0.0")]
356    pub const FRAC_1_SQRT_2: f32 = 0.707106781186547524400844362104849039_f32;
357
358    /// sqrt(3)
359    #[unstable(feature = "more_float_constants", issue = "146939")]
360    pub const SQRT_3: f32 = 1.732050807568877293527446341505872367_f32;
361
362    /// 1/sqrt(3)
363    #[unstable(feature = "more_float_constants", issue = "146939")]
364    pub const FRAC_1_SQRT_3: f32 = 0.577350269189625764509148780501957456_f32;
365
366    /// sqrt(5)
367    #[unstable(feature = "more_float_constants", issue = "146939")]
368    pub const SQRT_5: f32 = 2.23606797749978969640917366873127623_f32;
369
370    /// 1/sqrt(5)
371    #[unstable(feature = "more_float_constants", issue = "146939")]
372    pub const FRAC_1_SQRT_5: f32 = 0.44721359549995793928183473374625524_f32;
373
374    /// Euler's number (e)
375    #[stable(feature = "rust1", since = "1.0.0")]
376    pub const E: f32 = 2.71828182845904523536028747135266250_f32;
377
378    /// log<sub>2</sub>(e)
379    #[stable(feature = "rust1", since = "1.0.0")]
380    pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
381
382    /// log<sub>2</sub>(10)
383    #[stable(feature = "extra_log_consts", since = "1.43.0")]
384    pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
385
386    /// log<sub>10</sub>(e)
387    #[stable(feature = "rust1", since = "1.0.0")]
388    pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
389
390    /// log<sub>10</sub>(2)
391    #[stable(feature = "extra_log_consts", since = "1.43.0")]
392    pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
393
394    /// ln(2)
395    #[stable(feature = "rust1", since = "1.0.0")]
396    pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
397
398    /// ln(10)
399    #[stable(feature = "rust1", since = "1.0.0")]
400    pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
401}
402
403#[doc(test(attr(allow(unused_features))))]
404impl f32 {
405    /// The radix or base of the internal representation of `f32`.
406    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
407    pub const RADIX: u32 = 2;
408
409    /// The size of this float type in bits.
410    #[unstable(feature = "float_bits_const", issue = "151073")]
411    pub const BITS: u32 = 32;
412
413    /// Number of significant digits in base 2.
414    ///
415    /// Note that the size of the mantissa in the bitwise representation is one
416    /// smaller than this since the leading 1 is not stored explicitly.
417    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
418    pub const MANTISSA_DIGITS: u32 = 24;
419
420    /// Approximate number of significant digits in base 10.
421    ///
422    /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
423    /// significant digits can be converted to `f32` and back without loss.
424    ///
425    /// Equal to floor(log<sub>10</sub>&nbsp;2<sup>[`MANTISSA_DIGITS`]&nbsp;&minus;&nbsp;1</sup>).
426    ///
427    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
428    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
429    pub const DIGITS: u32 = 6;
430
431    /// [Machine epsilon] value for `f32`.
432    ///
433    /// This is the difference between `1.0` and the next larger representable number.
434    ///
435    /// Equal to 2<sup>1&nbsp;&minus;&nbsp;[`MANTISSA_DIGITS`]</sup>.
436    ///
437    /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
438    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
439    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
440    #[rustc_diagnostic_item = "f32_epsilon"]
441    pub const EPSILON: f32 = 1.19209290e-07_f32;
442
443    /// Smallest finite `f32` value.
444    ///
445    /// Equal to &minus;[`MAX`].
446    ///
447    /// [`MAX`]: f32::MAX
448    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
449    pub const MIN: f32 = -3.40282347e+38_f32;
450    /// Smallest positive normal `f32` value.
451    ///
452    /// Equal to 2<sup>[`MIN_EXP`]&nbsp;&minus;&nbsp;1</sup>.
453    ///
454    /// [`MIN_EXP`]: f32::MIN_EXP
455    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
456    pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
457    /// Largest finite `f32` value.
458    ///
459    /// Equal to
460    /// (1&nbsp;&minus;&nbsp;2<sup>&minus;[`MANTISSA_DIGITS`]</sup>)&nbsp;2<sup>[`MAX_EXP`]</sup>.
461    ///
462    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
463    /// [`MAX_EXP`]: f32::MAX_EXP
464    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
465    pub const MAX: f32 = 3.40282347e+38_f32;
466
467    /// One greater than the minimum possible *normal* power of 2 exponent
468    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
469    ///
470    /// This corresponds to the exact minimum possible *normal* power of 2 exponent
471    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
472    /// In other words, all normal numbers representable by this type are
473    /// greater than or equal to 0.5&nbsp;×&nbsp;2<sup><i>MIN_EXP</i></sup>.
474    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
475    pub const MIN_EXP: i32 = -125;
476    /// One greater than the maximum possible power of 2 exponent
477    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
478    ///
479    /// This corresponds to the exact maximum possible power of 2 exponent
480    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
481    /// In other words, all numbers representable by this type are
482    /// strictly less than 2<sup><i>MAX_EXP</i></sup>.
483    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
484    pub const MAX_EXP: i32 = 128;
485
486    /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
487    ///
488    /// Equal to ceil(log<sub>10</sub>&nbsp;[`MIN_POSITIVE`]).
489    ///
490    /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
491    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
492    pub const MIN_10_EXP: i32 = -37;
493    /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
494    ///
495    /// Equal to floor(log<sub>10</sub>&nbsp;[`MAX`]).
496    ///
497    /// [`MAX`]: f32::MAX
498    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
499    pub const MAX_10_EXP: i32 = 38;
500
501    /// Not a Number (NaN).
502    ///
503    /// Note that IEEE 754 doesn't define just a single NaN value; a plethora of bit patterns are
504    /// considered to be NaN. Furthermore, the standard makes a difference between a "signaling" and
505    /// a "quiet" NaN, and allows inspecting its "payload" (the unspecified bits in the bit pattern)
506    /// and its sign. See the [specification of NaN bit patterns](f32#nan-bit-patterns) for more
507    /// info.
508    ///
509    /// This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions
510    /// that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is
511    /// guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary.
512    /// The concrete bit pattern may change across Rust versions and target platforms.
513    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
514    #[rustc_diagnostic_item = "f32_nan"]
515    #[allow(clippy::eq_op, clippy::zero_divided_by_zero)]
516    pub const NAN: f32 = 0.0_f32 / 0.0_f32;
517    /// Infinity (∞).
518    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
519    pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
520    /// Negative infinity (−∞).
521    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
522    pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
523
524    /// Maximum integer that can be represented exactly in an [`f32`] value,
525    /// with no other integer converting to the same floating point value.
526    ///
527    /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
528    /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
529    /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
530    /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
531    /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
532    /// "one-to-one" mapping.
533    ///
534    /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
535    /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
536    /// ```
537    /// #![feature(float_exact_integer_constants)]
538    /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
539    /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
540    /// let max_exact_int = f32::MAX_EXACT_INTEGER;
541    /// assert_eq!(max_exact_int, max_exact_int as f32 as i32);
542    /// assert_eq!(max_exact_int + 1, (max_exact_int + 1) as f32 as i32);
543    /// assert_ne!(max_exact_int + 2, (max_exact_int + 2) as f32 as i32);
544    ///
545    /// // Beyond `f32::MAX_EXACT_INTEGER`, multiple integers can map to one float value
546    /// assert_eq!((max_exact_int + 1) as f32, (max_exact_int + 2) as f32);
547    /// # }
548    /// ```
549    #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
550    pub const MAX_EXACT_INTEGER: i32 = (1 << Self::MANTISSA_DIGITS) - 1;
551
552    /// Minimum integer that can be represented exactly in an [`f32`] value,
553    /// with no other integer converting to the same floating point value.
554    ///
555    /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
556    /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
557    /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
558    /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
559    /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
560    /// "one-to-one" mapping.
561    ///
562    /// This constant is equivalent to `-MAX_EXACT_INTEGER`.
563    ///
564    /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
565    /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
566    /// ```
567    /// #![feature(float_exact_integer_constants)]
568    /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
569    /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
570    /// let min_exact_int = f32::MIN_EXACT_INTEGER;
571    /// assert_eq!(min_exact_int, min_exact_int as f32 as i32);
572    /// assert_eq!(min_exact_int - 1, (min_exact_int - 1) as f32 as i32);
573    /// assert_ne!(min_exact_int - 2, (min_exact_int - 2) as f32 as i32);
574    ///
575    /// // Below `f32::MIN_EXACT_INTEGER`, multiple integers can map to one float value
576    /// assert_eq!((min_exact_int - 1) as f32, (min_exact_int - 2) as f32);
577    /// # }
578    /// ```
579    #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
580    pub const MIN_EXACT_INTEGER: i32 = -Self::MAX_EXACT_INTEGER;
581
582    /// The mask of the bit used to encode the sign of an [`f32`].
583    ///
584    /// This bit is set when the sign is negative and unset when the sign is
585    /// positive.
586    /// If you only need to check whether a value is positive or negative,
587    /// [`is_sign_positive`] or [`is_sign_negative`] can be used.
588    ///
589    /// [`is_sign_positive`]: f32::is_sign_positive
590    /// [`is_sign_negative`]: f32::is_sign_negative
591    /// ```rust
592    /// #![feature(float_masks)]
593    /// let sign_mask = f32::SIGN_MASK;
594    /// let a = 1.6552f32;
595    /// let a_bits = a.to_bits();
596    ///
597    /// assert_eq!(a_bits & sign_mask, 0x0);
598    /// assert_eq!(f32::from_bits(a_bits ^ sign_mask), -a);
599    /// assert_eq!(sign_mask, (-0.0f32).to_bits());
600    /// ```
601    #[unstable(feature = "float_masks", issue = "154064")]
602    pub const SIGN_MASK: u32 = 0x8000_0000;
603
604    /// The mask of the bits used to encode the exponent of an [`f32`].
605    ///
606    /// Note that the exponent is stored as a biased value, with a bias of 127 for `f32`.
607    ///
608    /// ```rust
609    /// #![feature(float_masks)]
610    /// fn get_exp(a: f32) -> i32 {
611    ///     let bias = 127;
612    ///     let biased = a.to_bits() & f32::EXPONENT_MASK;
613    ///     (biased >> (f32::MANTISSA_DIGITS - 1)).cast_signed() - bias
614    /// }
615    ///
616    /// assert_eq!(get_exp(0.5), -1);
617    /// assert_eq!(get_exp(1.0), 0);
618    /// assert_eq!(get_exp(2.0), 1);
619    /// assert_eq!(get_exp(4.0), 2);
620    /// ```
621    #[unstable(feature = "float_masks", issue = "154064")]
622    pub const EXPONENT_MASK: u32 = 0x7f80_0000;
623
624    /// The mask of the bits used to encode the mantissa of an [`f32`].
625    ///
626    /// ```rust
627    /// #![feature(float_masks)]
628    /// let mantissa_mask = f32::MANTISSA_MASK;
629    ///
630    /// assert_eq!(0f32.to_bits() & mantissa_mask, 0x0);
631    /// assert_eq!(1f32.to_bits() & mantissa_mask, 0x0);
632    ///
633    /// // multiplying a finite value by a power of 2 doesn't change its mantissa
634    /// // unless the result or initial value is not normal.
635    /// let a = 1.6552f32;
636    /// let b = 4.0 * a;
637    /// assert_eq!(a.to_bits() & mantissa_mask, b.to_bits() & mantissa_mask);
638    ///
639    /// // The maximum and minimum values have a saturated significand
640    /// assert_eq!(f32::MAX.to_bits() & f32::MANTISSA_MASK, f32::MANTISSA_MASK);
641    /// assert_eq!(f32::MIN.to_bits() & f32::MANTISSA_MASK, f32::MANTISSA_MASK);
642    /// ```
643    #[unstable(feature = "float_masks", issue = "154064")]
644    pub const MANTISSA_MASK: u32 = 0x007f_ffff;
645
646    /// Minimum representable positive value (min subnormal)
647    const TINY_BITS: u32 = 0x1;
648
649    /// Minimum representable negative value (min negative subnormal)
650    const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
651
652    /// Returns `true` if this value is NaN.
653    ///
654    /// ```
655    /// let nan = f32::NAN;
656    /// let f = 7.0_f32;
657    ///
658    /// assert!(nan.is_nan());
659    /// assert!(!f.is_nan());
660    /// ```
661    #[must_use]
662    #[stable(feature = "rust1", since = "1.0.0")]
663    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
664    #[inline]
665    #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
666    pub const fn is_nan(self) -> bool {
667        self != self
668    }
669
670    /// Returns `true` if this value is positive infinity or negative infinity, and
671    /// `false` otherwise.
672    ///
673    /// ```
674    /// let f = 7.0f32;
675    /// let inf = f32::INFINITY;
676    /// let neg_inf = f32::NEG_INFINITY;
677    /// let nan = f32::NAN;
678    ///
679    /// assert!(!f.is_infinite());
680    /// assert!(!nan.is_infinite());
681    ///
682    /// assert!(inf.is_infinite());
683    /// assert!(neg_inf.is_infinite());
684    /// ```
685    #[must_use]
686    #[stable(feature = "rust1", since = "1.0.0")]
687    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
688    #[inline]
689    pub const fn is_infinite(self) -> bool {
690        // Getting clever with transmutation can result in incorrect answers on some FPUs
691        // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
692        // See https://github.com/rust-lang/rust/issues/72327
693        (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
694    }
695
696    /// Returns `true` if this number is neither infinite nor NaN.
697    ///
698    /// ```
699    /// let f = 7.0f32;
700    /// let inf = f32::INFINITY;
701    /// let neg_inf = f32::NEG_INFINITY;
702    /// let nan = f32::NAN;
703    ///
704    /// assert!(f.is_finite());
705    ///
706    /// assert!(!nan.is_finite());
707    /// assert!(!inf.is_finite());
708    /// assert!(!neg_inf.is_finite());
709    /// ```
710    #[must_use]
711    #[stable(feature = "rust1", since = "1.0.0")]
712    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
713    #[inline]
714    pub const fn is_finite(self) -> bool {
715        // There's no need to handle NaN separately: if self is NaN,
716        // the comparison is not true, exactly as desired.
717        self.abs() < Self::INFINITY
718    }
719
720    /// Returns `true` if the number is [subnormal].
721    ///
722    /// ```
723    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
724    /// let max = f32::MAX;
725    /// let lower_than_min = 1.0e-40_f32;
726    /// let zero = 0.0_f32;
727    ///
728    /// assert!(!min.is_subnormal());
729    /// assert!(!max.is_subnormal());
730    ///
731    /// assert!(!zero.is_subnormal());
732    /// assert!(!f32::NAN.is_subnormal());
733    /// assert!(!f32::INFINITY.is_subnormal());
734    /// // Values between `0` and `min` are Subnormal.
735    /// assert!(lower_than_min.is_subnormal());
736    /// ```
737    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
738    #[must_use]
739    #[stable(feature = "is_subnormal", since = "1.53.0")]
740    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
741    #[inline]
742    pub const fn is_subnormal(self) -> bool {
743        matches!(self.classify(), FpCategory::Subnormal)
744    }
745
746    /// Returns `true` if the number is neither zero, infinite,
747    /// [subnormal], or NaN.
748    ///
749    /// ```
750    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
751    /// let max = f32::MAX;
752    /// let lower_than_min = 1.0e-40_f32;
753    /// let zero = 0.0_f32;
754    ///
755    /// assert!(min.is_normal());
756    /// assert!(max.is_normal());
757    ///
758    /// assert!(!zero.is_normal());
759    /// assert!(!f32::NAN.is_normal());
760    /// assert!(!f32::INFINITY.is_normal());
761    /// // Values between `0` and `min` are Subnormal.
762    /// assert!(!lower_than_min.is_normal());
763    /// ```
764    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
765    #[must_use]
766    #[stable(feature = "rust1", since = "1.0.0")]
767    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
768    #[inline]
769    pub const fn is_normal(self) -> bool {
770        matches!(self.classify(), FpCategory::Normal)
771    }
772
773    /// Returns the floating point category of the number. If only one property
774    /// is going to be tested, it is generally faster to use the specific
775    /// predicate instead.
776    ///
777    /// ```
778    /// use std::num::FpCategory;
779    ///
780    /// let num = 12.4_f32;
781    /// let inf = f32::INFINITY;
782    ///
783    /// assert_eq!(num.classify(), FpCategory::Normal);
784    /// assert_eq!(inf.classify(), FpCategory::Infinite);
785    /// ```
786    #[stable(feature = "rust1", since = "1.0.0")]
787    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
788    #[must_use]
789    pub const fn classify(self) -> FpCategory {
790        // We used to have complicated logic here that avoids the simple bit-based tests to work
791        // around buggy codegen for x87 targets (see
792        // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
793        // of our tests is able to find any difference between the complicated and the naive
794        // version, so now we are back to the naive version.
795        let b = self.to_bits();
796        match (b & Self::MANTISSA_MASK, b & Self::EXPONENT_MASK) {
797            (0, Self::EXPONENT_MASK) => FpCategory::Infinite,
798            (_, Self::EXPONENT_MASK) => FpCategory::Nan,
799            (0, 0) => FpCategory::Zero,
800            (_, 0) => FpCategory::Subnormal,
801            _ => FpCategory::Normal,
802        }
803    }
804
805    /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
806    /// positive sign bit and positive infinity.
807    ///
808    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
809    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
810    /// conserved over arithmetic operations, the result of `is_sign_positive` on
811    /// a NaN might produce an unexpected or non-portable result. See the [specification
812    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
813    /// if you need fully portable behavior (will return `false` for all NaNs).
814    ///
815    /// ```
816    /// let f = 7.0_f32;
817    /// let g = -7.0_f32;
818    ///
819    /// assert!(f.is_sign_positive());
820    /// assert!(!g.is_sign_positive());
821    /// ```
822    #[must_use]
823    #[stable(feature = "rust1", since = "1.0.0")]
824    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
825    #[inline]
826    pub const fn is_sign_positive(self) -> bool {
827        !self.is_sign_negative()
828    }
829
830    /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
831    /// negative sign bit and negative infinity.
832    ///
833    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
834    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
835    /// conserved over arithmetic operations, the result of `is_sign_negative` on
836    /// a NaN might produce an unexpected or non-portable result. See the [specification
837    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
838    /// if you need fully portable behavior (will return `false` for all NaNs).
839    ///
840    /// ```
841    /// let f = 7.0f32;
842    /// let g = -7.0f32;
843    ///
844    /// assert!(!f.is_sign_negative());
845    /// assert!(g.is_sign_negative());
846    /// ```
847    #[must_use]
848    #[stable(feature = "rust1", since = "1.0.0")]
849    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
850    #[inline]
851    pub const fn is_sign_negative(self) -> bool {
852        // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
853        // applies to zeros and NaNs as well.
854        self.to_bits() & 0x8000_0000 != 0
855    }
856
857    /// Returns the least number greater than `self`.
858    ///
859    /// Let `TINY` be the smallest representable positive `f32`. Then,
860    ///  - if `self.is_nan()`, this returns `self`;
861    ///  - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
862    ///  - if `self` is `-TINY`, this returns -0.0;
863    ///  - if `self` is -0.0 or +0.0, this returns `TINY`;
864    ///  - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
865    ///  - otherwise the unique least value greater than `self` is returned.
866    ///
867    /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
868    /// is finite `x == x.next_up().next_down()` also holds.
869    ///
870    /// ```rust
871    /// // f32::EPSILON is the difference between 1.0 and the next number up.
872    /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
873    /// // But not for most numbers.
874    /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
875    /// assert_eq!(16777216f32.next_up(), 16777218.0);
876    /// ```
877    ///
878    /// This operation corresponds to IEEE-754 `nextUp`.
879    ///
880    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
881    /// [`INFINITY`]: Self::INFINITY
882    /// [`MIN`]: Self::MIN
883    /// [`MAX`]: Self::MAX
884    #[inline]
885    #[doc(alias = "nextUp")]
886    #[stable(feature = "float_next_up_down", since = "1.86.0")]
887    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
888    #[must_use = "method returns a new number and does not mutate the original value"]
889    pub const fn next_up(self) -> Self {
890        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
891        // denormals to zero. This is in general unsound and unsupported, but here
892        // we do our best to still produce the correct result on such targets.
893        let bits = self.to_bits();
894        if self.is_nan() || bits == Self::INFINITY.to_bits() {
895            return self;
896        }
897
898        let abs = bits & !Self::SIGN_MASK;
899        let next_bits = if abs == 0 {
900            Self::TINY_BITS
901        } else if bits == abs {
902            bits + 1
903        } else {
904            bits - 1
905        };
906        Self::from_bits(next_bits)
907    }
908
909    /// Returns the greatest number less than `self`.
910    ///
911    /// Let `TINY` be the smallest representable positive `f32`. Then,
912    ///  - if `self.is_nan()`, this returns `self`;
913    ///  - if `self` is [`INFINITY`], this returns [`MAX`];
914    ///  - if `self` is `TINY`, this returns 0.0;
915    ///  - if `self` is -0.0 or +0.0, this returns `-TINY`;
916    ///  - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
917    ///  - otherwise the unique greatest value less than `self` is returned.
918    ///
919    /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
920    /// is finite `x == x.next_down().next_up()` also holds.
921    ///
922    /// ```rust
923    /// let x = 1.0f32;
924    /// // Clamp value into range [0, 1).
925    /// let clamped = x.clamp(0.0, 1.0f32.next_down());
926    /// assert!(clamped < 1.0);
927    /// assert_eq!(clamped.next_up(), 1.0);
928    /// ```
929    ///
930    /// This operation corresponds to IEEE-754 `nextDown`.
931    ///
932    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
933    /// [`INFINITY`]: Self::INFINITY
934    /// [`MIN`]: Self::MIN
935    /// [`MAX`]: Self::MAX
936    #[inline]
937    #[doc(alias = "nextDown")]
938    #[stable(feature = "float_next_up_down", since = "1.86.0")]
939    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
940    #[must_use = "method returns a new number and does not mutate the original value"]
941    pub const fn next_down(self) -> Self {
942        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
943        // denormals to zero. This is in general unsound and unsupported, but here
944        // we do our best to still produce the correct result on such targets.
945        let bits = self.to_bits();
946        if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
947            return self;
948        }
949
950        let abs = bits & !Self::SIGN_MASK;
951        let next_bits = if abs == 0 {
952            Self::NEG_TINY_BITS
953        } else if bits == abs {
954            bits - 1
955        } else {
956            bits + 1
957        };
958        Self::from_bits(next_bits)
959    }
960
961    /// Takes the reciprocal (inverse) of a number, `1/x`.
962    ///
963    /// ```
964    /// let x = 2.0_f32;
965    /// let abs_difference = (x.recip() - (1.0 / x)).abs();
966    ///
967    /// assert!(abs_difference <= f32::EPSILON);
968    /// ```
969    #[must_use = "this returns the result of the operation, without modifying the original"]
970    #[stable(feature = "rust1", since = "1.0.0")]
971    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
972    #[inline]
973    pub const fn recip(self) -> f32 {
974        1.0 / self
975    }
976
977    /// Converts radians to degrees.
978    ///
979    /// # Unspecified precision
980    ///
981    /// The precision of this function is non-deterministic. This means it varies by platform,
982    /// Rust version, and can even differ within the same execution from one invocation to the next.
983    ///
984    /// # Examples
985    ///
986    /// ```
987    /// let angle = std::f32::consts::PI;
988    ///
989    /// let abs_difference = (angle.to_degrees() - 180.0).abs();
990    /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
991    /// assert!(abs_difference <= f32::EPSILON);
992    /// ```
993    #[must_use = "this returns the result of the operation, \
994                  without modifying the original"]
995    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
996    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
997    #[inline]
998    pub const fn to_degrees(self) -> f32 {
999        // Use a literal to avoid double rounding, consts::PI is already rounded,
1000        // and dividing would round again.
1001        const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
1002        self * PIS_IN_180
1003    }
1004
1005    /// Converts degrees to radians.
1006    ///
1007    /// # Unspecified precision
1008    ///
1009    /// The precision of this function is non-deterministic. This means it varies by platform,
1010    /// Rust version, and can even differ within the same execution from one invocation to the next.
1011    ///
1012    /// # Examples
1013    ///
1014    /// ```
1015    /// let angle = 180.0f32;
1016    ///
1017    /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
1018    ///
1019    /// assert!(abs_difference <= f32::EPSILON);
1020    /// ```
1021    #[must_use = "this returns the result of the operation, \
1022                  without modifying the original"]
1023    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
1024    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1025    #[inline]
1026    pub const fn to_radians(self) -> f32 {
1027        // The division here is correctly rounded with respect to the true value of π/180.
1028        // Although π is irrational and already rounded, the double rounding happens
1029        // to produce correct result for f32.
1030        const RADS_PER_DEG: f32 = consts::PI / 180.0;
1031        self * RADS_PER_DEG
1032    }
1033
1034    /// Returns the maximum of the two numbers, ignoring NaN.
1035    ///
1036    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
1037    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1038    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1039    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1040    /// non-deterministically.
1041    ///
1042    /// The handling of NaNs follows the IEEE 754-2019 semantics for `maximumNumber`, treating all
1043    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1044    /// follows the IEEE 754-2008 semantics for `maxNum`.
1045    ///
1046    /// ```
1047    /// let x = 1.0f32;
1048    /// let y = 2.0f32;
1049    ///
1050    /// assert_eq!(x.max(y), y);
1051    /// assert_eq!(x.max(f32::NAN), x);
1052    /// ```
1053    #[must_use = "this returns the result of the comparison, without modifying either input"]
1054    #[stable(feature = "rust1", since = "1.0.0")]
1055    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1056    #[inline]
1057    pub const fn max(self, other: f32) -> f32 {
1058        intrinsics::maximum_number_nsz_f32(self, other)
1059    }
1060
1061    /// Returns the minimum of the two numbers, ignoring NaN.
1062    ///
1063    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
1064    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1065    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1066    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1067    /// non-deterministically.
1068    ///
1069    /// The handling of NaNs follows the IEEE 754-2019 semantics for `minimumNumber`, treating all
1070    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1071    /// follows the IEEE 754-2008 semantics for `minNum`.
1072    ///
1073    /// ```
1074    /// let x = 1.0f32;
1075    /// let y = 2.0f32;
1076    ///
1077    /// assert_eq!(x.min(y), x);
1078    /// assert_eq!(x.min(f32::NAN), x);
1079    /// ```
1080    #[must_use = "this returns the result of the comparison, without modifying either input"]
1081    #[stable(feature = "rust1", since = "1.0.0")]
1082    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1083    #[inline]
1084    pub const fn min(self, other: f32) -> f32 {
1085        intrinsics::minimum_number_nsz_f32(self, other)
1086    }
1087
1088    /// Returns the maximum of the two numbers, propagating NaN.
1089    ///
1090    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1091    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1092    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1093    /// non-NaN inputs.
1094    ///
1095    /// This is in contrast to [`f32::max`] which only returns NaN when *both* arguments are NaN,
1096    /// and which does not reliably order `-0.0` and `+0.0`.
1097    ///
1098    /// This follows the IEEE 754-2019 semantics for `maximum`.
1099    ///
1100    /// ```
1101    /// #![feature(float_minimum_maximum)]
1102    /// let x = 1.0f32;
1103    /// let y = 2.0f32;
1104    ///
1105    /// assert_eq!(x.maximum(y), y);
1106    /// assert!(x.maximum(f32::NAN).is_nan());
1107    /// ```
1108    #[must_use = "this returns the result of the comparison, without modifying either input"]
1109    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1110    #[inline]
1111    pub const fn maximum(self, other: f32) -> f32 {
1112        intrinsics::maximumf32(self, other)
1113    }
1114
1115    /// Returns the minimum of the two numbers, propagating NaN.
1116    ///
1117    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1118    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1119    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1120    /// non-NaN inputs.
1121    ///
1122    /// This is in contrast to [`f32::min`] which only returns NaN when *both* arguments are NaN,
1123    /// and which does not reliably order `-0.0` and `+0.0`.
1124    ///
1125    /// This follows the IEEE 754-2019 semantics for `minimum`.
1126    ///
1127    /// ```
1128    /// #![feature(float_minimum_maximum)]
1129    /// let x = 1.0f32;
1130    /// let y = 2.0f32;
1131    ///
1132    /// assert_eq!(x.minimum(y), x);
1133    /// assert!(x.minimum(f32::NAN).is_nan());
1134    /// ```
1135    #[must_use = "this returns the result of the comparison, without modifying either input"]
1136    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1137    #[inline]
1138    pub const fn minimum(self, other: f32) -> f32 {
1139        intrinsics::minimumf32(self, other)
1140    }
1141
1142    /// Calculates the midpoint (average) between `self` and `rhs`.
1143    ///
1144    /// This returns NaN when *either* argument is NaN or if a combination of
1145    /// +inf and -inf is provided as arguments.
1146    ///
1147    /// # Examples
1148    ///
1149    /// ```
1150    /// assert_eq!(1f32.midpoint(4.0), 2.5);
1151    /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1152    /// ```
1153    #[inline]
1154    #[doc(alias = "average")]
1155    #[stable(feature = "num_midpoint", since = "1.85.0")]
1156    #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1157    #[must_use = "this returns the result of the operation, \
1158                  without modifying the original"]
1159    pub const fn midpoint(self, other: f32) -> f32 {
1160        cfg_select! {
1161            // Allow faster implementation that have known good 64-bit float
1162            // implementations. Falling back to the branchy code on targets that don't
1163            // have 64-bit hardware floats or buggy implementations.
1164            // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1165            any(
1166                target_arch = "x86_64",
1167                target_arch = "aarch64",
1168                all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1169                all(target_arch = "loongarch64", target_feature = "d"),
1170                all(target_arch = "arm", target_feature = "vfp2"),
1171                target_arch = "wasm32",
1172                target_arch = "wasm64",
1173            ) => ((self as f64 + other as f64) * 0.5) as f32,
1174            _ => {
1175                const HI: f32 = f32::MAX * 0.5;
1176
1177                let (a, b) = (self, other);
1178                let abs_a = a.abs();
1179                let abs_b = b.abs();
1180
1181                if abs_a <= HI && abs_b <= HI {
1182                    // Overflow is impossible
1183                    (a + b) * 0.5
1184                } else {
1185                    (a * 0.5) + (b * 0.5)
1186                }
1187            }
1188        }
1189    }
1190
1191    /// Rounds toward zero and converts to any primitive integer type,
1192    /// assuming that the value is finite and fits in that type.
1193    ///
1194    /// ```
1195    /// let value = 4.6_f32;
1196    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1197    /// assert_eq!(rounded, 4);
1198    ///
1199    /// let value = -128.9_f32;
1200    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1201    /// assert_eq!(rounded, i8::MIN);
1202    /// ```
1203    ///
1204    /// # Safety
1205    ///
1206    /// The value must:
1207    ///
1208    /// * Not be `NaN`
1209    /// * Not be infinite
1210    /// * Be representable in the return type `Int`, after truncating off its fractional part
1211    #[must_use = "this returns the result of the operation, \
1212                  without modifying the original"]
1213    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1214    #[inline]
1215    pub unsafe fn to_int_unchecked<Int>(self) -> Int
1216    where
1217        Self: FloatToInt<Int>,
1218    {
1219        // SAFETY: the caller must uphold the safety contract for
1220        // `FloatToInt::to_int_unchecked`.
1221        unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1222    }
1223
1224    /// Converts to the target float type, rounding as defined in IEEE 754.
1225    ///
1226    /// This is equivalent to `self as Flt`. Narrowing to a smaller type can
1227    /// produce an infinity.
1228    ///
1229    /// ```
1230    /// #![feature(float_conversions)]
1231    ///
1232    /// let x = 1.5_f32;
1233    /// assert_eq!(x.cast::<f64>(), 1.5_f64);
1234    /// ```
1235    #[unstable(feature = "float_conversions", issue = "159913")]
1236    #[must_use = "this returns the result of the operation, \
1237                  without modifying the original"]
1238    #[inline]
1239    pub fn cast<Flt>(self) -> Flt
1240    where
1241        Self: FloatToFloat<Flt>,
1242    {
1243        FloatToFloat::<Flt>::cast(self)
1244    }
1245
1246    /// Rounds toward zero and converts to any primitive integer type, saturating
1247    /// at the type's boundaries and mapping `NaN` to zero.
1248    ///
1249    /// This is equivalent to `self as Int`.
1250    ///
1251    /// ```
1252    /// #![feature(float_conversions)]
1253    ///
1254    /// assert_eq!(255.5_f32.to_int_saturating::<u8>(), 255);
1255    /// assert_eq!(300.0_f32.to_int_saturating::<u8>(), 255);
1256    /// assert_eq!((-1.0_f32).to_int_saturating::<u8>(), 0);
1257    /// assert_eq!(f32::NAN.to_int_saturating::<u8>(), 0);
1258    /// ```
1259    #[unstable(feature = "float_conversions", issue = "159913")]
1260    #[must_use = "this returns the result of the operation, \
1261                  without modifying the original"]
1262    #[inline]
1263    pub fn to_int_saturating<Int>(self) -> Int
1264    where
1265        Self: FloatToInt<Int>,
1266    {
1267        FloatToInt::<Int>::to_int_saturating(self)
1268    }
1269
1270    /// Rounds toward zero and converts to any primitive integer type, returning
1271    /// `None` if the value is `NaN`, infinite, or does not fit in the target type.
1272    ///
1273    /// ```
1274    /// #![feature(float_conversions)]
1275    ///
1276    /// assert_eq!(255.5_f32.to_int_checked::<u8>(), Some(255));
1277    /// assert_eq!(256.0_f32.to_int_checked::<u8>(), None);
1278    /// assert_eq!(f32::NAN.to_int_checked::<u8>(), None);
1279    /// ```
1280    #[unstable(feature = "float_conversions", issue = "159913")]
1281    #[must_use = "this returns the result of the operation, \
1282                  without modifying the original"]
1283    #[inline]
1284    pub fn to_int_checked<Int>(self) -> Option<Int>
1285    where
1286        Self: FloatToInt<Int>,
1287    {
1288        FloatToInt::<Int>::to_int_checked(self)
1289    }
1290
1291    /// Rounds toward zero and converts to any primitive integer type.
1292    ///
1293    /// This is equivalent to `self.to_int_checked().unwrap()`.
1294    ///
1295    /// # Panics
1296    ///
1297    /// Panics if the value is `NaN`, infinite, or does not fit in the target type.
1298    ///
1299    /// ```
1300    /// #![feature(float_conversions)]
1301    ///
1302    /// assert_eq!(255.5_f32.to_int_strict::<u8>(), 255);
1303    /// ```
1304    #[unstable(feature = "float_conversions", issue = "159913")]
1305    #[must_use = "this returns the result of the operation, \
1306                  without modifying the original"]
1307    #[inline]
1308    #[track_caller]
1309    pub fn to_int_strict<Int>(self) -> Int
1310    where
1311        Self: FloatToInt<Int>,
1312    {
1313        self.to_int_checked::<Int>()
1314            .expect("the value cannot be represented in the target integer type")
1315    }
1316
1317    /// Raw transmutation to `u32`.
1318    ///
1319    /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1320    ///
1321    /// See [`from_bits`](Self::from_bits) for some discussion of the
1322    /// portability of this operation (there are almost no issues).
1323    ///
1324    /// Note that this function is distinct from `as` casting, which attempts to
1325    /// preserve the *numeric* value, and not the bitwise value.
1326    ///
1327    /// # Examples
1328    ///
1329    /// ```
1330    /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1331    /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1332    ///
1333    /// ```
1334    #[must_use = "this returns the result of the operation, \
1335                  without modifying the original"]
1336    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1337    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1338    #[inline]
1339    #[allow(unnecessary_transmutes)]
1340    pub const fn to_bits(self) -> u32 {
1341        // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1342        unsafe { mem::transmute(self) }
1343    }
1344
1345    /// Raw transmutation from `u32`.
1346    ///
1347    /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1348    /// It turns out this is incredibly portable, for two reasons:
1349    ///
1350    /// * Floats and Ints have the same endianness on all supported platforms.
1351    /// * IEEE 754 very precisely specifies the bit layout of floats.
1352    ///
1353    /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1354    /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1355    /// (notably x86 and ARM) picked the interpretation that was ultimately
1356    /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1357    /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1358    ///
1359    /// Rather than trying to preserve signaling-ness cross-platform, this
1360    /// implementation favors preserving the exact bits. This means that
1361    /// any payloads encoded in NaNs will be preserved even if the result of
1362    /// this method is sent over the network from an x86 machine to a MIPS one.
1363    ///
1364    /// If the results of this method are only manipulated by the same
1365    /// architecture that produced them, then there is no portability concern.
1366    ///
1367    /// If the input isn't NaN, then there is no portability concern.
1368    ///
1369    /// If you don't care about signalingness (very likely), then there is no
1370    /// portability concern.
1371    ///
1372    /// Note that this function is distinct from `as` casting, which attempts to
1373    /// preserve the *numeric* value, and not the bitwise value.
1374    ///
1375    /// # Examples
1376    ///
1377    /// ```
1378    /// let v = f32::from_bits(0x41480000);
1379    /// assert_eq!(v, 12.5);
1380    /// ```
1381    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1382    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1383    #[must_use]
1384    #[inline]
1385    #[allow(unnecessary_transmutes)]
1386    pub const fn from_bits(v: u32) -> Self {
1387        // It turns out the safety issues with sNaN were overblown! Hooray!
1388        // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1389        unsafe { mem::transmute(v) }
1390    }
1391
1392    /// Returns the memory representation of this floating point number as a byte array in
1393    /// big-endian (network) byte order.
1394    ///
1395    /// See [`from_bits`](Self::from_bits) for some discussion of the
1396    /// portability of this operation (there are almost no issues).
1397    ///
1398    /// # Examples
1399    ///
1400    /// ```
1401    /// let bytes = 12.5f32.to_be_bytes();
1402    /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1403    /// ```
1404    #[must_use = "this returns the result of the operation, \
1405                  without modifying the original"]
1406    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1407    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1408    #[inline]
1409    pub const fn to_be_bytes(self) -> [u8; 4] {
1410        self.to_bits().to_be_bytes()
1411    }
1412
1413    /// Returns the memory representation of this floating point number as a byte array in
1414    /// little-endian byte order.
1415    ///
1416    /// See [`from_bits`](Self::from_bits) for some discussion of the
1417    /// portability of this operation (there are almost no issues).
1418    ///
1419    /// # Examples
1420    ///
1421    /// ```
1422    /// let bytes = 12.5f32.to_le_bytes();
1423    /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1424    /// ```
1425    #[must_use = "this returns the result of the operation, \
1426                  without modifying the original"]
1427    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1428    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1429    #[inline]
1430    pub const fn to_le_bytes(self) -> [u8; 4] {
1431        self.to_bits().to_le_bytes()
1432    }
1433
1434    /// Returns the memory representation of this floating point number as a byte array in
1435    /// native byte order.
1436    ///
1437    /// As the target platform's native endianness is used, portable code
1438    /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1439    ///
1440    /// [`to_be_bytes`]: f32::to_be_bytes
1441    /// [`to_le_bytes`]: f32::to_le_bytes
1442    ///
1443    /// See [`from_bits`](Self::from_bits) for some discussion of the
1444    /// portability of this operation (there are almost no issues).
1445    ///
1446    /// # Examples
1447    ///
1448    /// ```
1449    /// let bytes = 12.5f32.to_ne_bytes();
1450    /// assert_eq!(
1451    ///     bytes,
1452    ///     if cfg!(target_endian = "big") {
1453    ///         [0x41, 0x48, 0x00, 0x00]
1454    ///     } else {
1455    ///         [0x00, 0x00, 0x48, 0x41]
1456    ///     }
1457    /// );
1458    /// ```
1459    #[must_use = "this returns the result of the operation, \
1460                  without modifying the original"]
1461    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1462    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1463    #[inline]
1464    pub const fn to_ne_bytes(self) -> [u8; 4] {
1465        self.to_bits().to_ne_bytes()
1466    }
1467
1468    /// Creates a floating point value from its representation as a byte array in big endian.
1469    ///
1470    /// See [`from_bits`](Self::from_bits) for some discussion of the
1471    /// portability of this operation (there are almost no issues).
1472    ///
1473    /// # Examples
1474    ///
1475    /// ```
1476    /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1477    /// assert_eq!(value, 12.5);
1478    /// ```
1479    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1480    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1481    #[must_use]
1482    #[inline]
1483    pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1484        Self::from_bits(u32::from_be_bytes(bytes))
1485    }
1486
1487    /// Creates a floating point value from its representation as a byte array in little endian.
1488    ///
1489    /// See [`from_bits`](Self::from_bits) for some discussion of the
1490    /// portability of this operation (there are almost no issues).
1491    ///
1492    /// # Examples
1493    ///
1494    /// ```
1495    /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1496    /// assert_eq!(value, 12.5);
1497    /// ```
1498    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1499    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1500    #[must_use]
1501    #[inline]
1502    pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1503        Self::from_bits(u32::from_le_bytes(bytes))
1504    }
1505
1506    /// Creates a floating point value from its representation as a byte array in native endian.
1507    ///
1508    /// As the target platform's native endianness is used, portable code
1509    /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1510    /// appropriate instead.
1511    ///
1512    /// [`from_be_bytes`]: f32::from_be_bytes
1513    /// [`from_le_bytes`]: f32::from_le_bytes
1514    ///
1515    /// See [`from_bits`](Self::from_bits) for some discussion of the
1516    /// portability of this operation (there are almost no issues).
1517    ///
1518    /// # Examples
1519    ///
1520    /// ```
1521    /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1522    ///     [0x41, 0x48, 0x00, 0x00]
1523    /// } else {
1524    ///     [0x00, 0x00, 0x48, 0x41]
1525    /// });
1526    /// assert_eq!(value, 12.5);
1527    /// ```
1528    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1529    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1530    #[must_use]
1531    #[inline]
1532    pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1533        Self::from_bits(u32::from_ne_bytes(bytes))
1534    }
1535
1536    /// Returns the ordering between `self` and `other`.
1537    ///
1538    /// Unlike the standard partial comparison between floating point numbers,
1539    /// this comparison always produces an ordering in accordance to
1540    /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1541    /// floating point standard. The values are ordered in the following sequence:
1542    ///
1543    /// - negative quiet NaN
1544    /// - negative signaling NaN
1545    /// - negative infinity
1546    /// - negative numbers
1547    /// - negative subnormal numbers
1548    /// - negative zero
1549    /// - positive zero
1550    /// - positive subnormal numbers
1551    /// - positive numbers
1552    /// - positive infinity
1553    /// - positive signaling NaN
1554    /// - positive quiet NaN.
1555    ///
1556    /// The ordering established by this function does not always agree with the
1557    /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1558    /// they consider negative and positive zero equal, while `total_cmp`
1559    /// doesn't.
1560    ///
1561    /// The interpretation of the signaling NaN bit follows the definition in
1562    /// the IEEE 754 standard, which may not match the interpretation by some of
1563    /// the older, non-conformant (e.g. MIPS) hardware implementations.
1564    ///
1565    /// # Example
1566    ///
1567    /// ```
1568    /// struct GoodBoy {
1569    ///     name: String,
1570    ///     weight: f32,
1571    /// }
1572    ///
1573    /// let mut bois = vec![
1574    ///     GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1575    ///     GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1576    ///     GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1577    ///     GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1578    ///     GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1579    ///     GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1580    /// ];
1581    ///
1582    /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1583    ///
1584    /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1585    /// if f32::NAN.is_sign_negative() {
1586    ///     assert!(bois.into_iter().map(|b| b.weight)
1587    ///         .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1588    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1589    /// } else {
1590    ///     assert!(bois.into_iter().map(|b| b.weight)
1591    ///         .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1592    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1593    /// }
1594    /// ```
1595    #[stable(feature = "total_cmp", since = "1.62.0")]
1596    #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1597    #[must_use]
1598    #[inline]
1599    pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1600        let mut left = self.to_bits() as i32;
1601        let mut right = other.to_bits() as i32;
1602
1603        // In case of negatives, flip all the bits except the sign
1604        // to achieve a similar layout as two's complement integers
1605        //
1606        // Why does this work? IEEE 754 floats consist of three fields:
1607        // Sign bit, exponent and mantissa. The set of exponent and mantissa
1608        // fields as a whole have the property that their bitwise order is
1609        // equal to the numeric magnitude where the magnitude is defined.
1610        // The magnitude is not normally defined on NaN values, but
1611        // IEEE 754 totalOrder defines the NaN values also to follow the
1612        // bitwise order. This leads to order explained in the doc comment.
1613        // However, the representation of magnitude is the same for negative
1614        // and positive numbers – only the sign bit is different.
1615        // To easily compare the floats as signed integers, we need to
1616        // flip the exponent and mantissa bits in case of negative numbers.
1617        // We effectively convert the numbers to "two's complement" form.
1618        //
1619        // To do the flipping, we construct a mask and XOR against it.
1620        // We branchlessly calculate an "all-ones except for the sign bit"
1621        // mask from negative-signed values: right shifting sign-extends
1622        // the integer, so we "fill" the mask with sign bits, and then
1623        // convert to unsigned to push one more zero bit.
1624        // On positive values, the mask is all zeros, so it's a no-op.
1625        left ^= (((left >> 31) as u32) >> 1) as i32;
1626        right ^= (((right >> 31) as u32) >> 1) as i32;
1627
1628        left.cmp(&right)
1629    }
1630
1631    /// Restrict a value to a certain interval unless it is NaN.
1632    ///
1633    /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1634    /// less than `min`. Otherwise this returns `self`.
1635    ///
1636    /// Note that this function returns NaN if the initial value was NaN as
1637    /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1638    /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1639    ///
1640    /// # Panics
1641    ///
1642    /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1643    ///
1644    /// # Examples
1645    ///
1646    /// ```
1647    /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1648    /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1649    /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1650    /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1651    ///
1652    /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1653    /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1654    /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1655    /// // This is definitely a negative zero.
1656    /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1657    /// ```
1658    #[must_use = "method returns a new number and does not mutate the original value"]
1659    #[stable(feature = "clamp", since = "1.50.0")]
1660    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1661    #[inline]
1662    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1663        const_assert!(
1664            min <= max,
1665            "min > max, or either was NaN",
1666            "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1667            min: f32,
1668            max: f32,
1669        );
1670
1671        if self < min {
1672            self = min;
1673        }
1674        if self > max {
1675            self = max;
1676        }
1677        self
1678    }
1679
1680    /// Clamps this number to a symmetric range centered around zero.
1681    ///
1682    /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1683    ///
1684    /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1685    /// explicit about the intent.
1686    ///
1687    /// # Panics
1688    ///
1689    /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1690    ///
1691    /// # Examples
1692    ///
1693    /// ```
1694    /// #![feature(clamp_magnitude)]
1695    /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1696    /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1697    /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1698    /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1699    /// ```
1700    #[must_use = "this returns the clamped value and does not modify the original"]
1701    #[unstable(feature = "clamp_magnitude", issue = "148519")]
1702    #[inline]
1703    pub fn clamp_magnitude(self, limit: f32) -> f32 {
1704        assert!(limit >= 0.0, "limit must be non-negative");
1705        let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1706        self.clamp(-limit, limit)
1707    }
1708
1709    /// Computes the absolute value of `self`.
1710    ///
1711    /// This function always returns the precise result.
1712    ///
1713    /// # Examples
1714    ///
1715    /// ```
1716    /// let x = 3.5_f32;
1717    /// let y = -3.5_f32;
1718    ///
1719    /// assert_eq!(x.abs(), x);
1720    /// assert_eq!(y.abs(), -y);
1721    ///
1722    /// assert!(f32::NAN.abs().is_nan());
1723    /// ```
1724    #[must_use = "method returns a new number and does not mutate the original value"]
1725    #[stable(feature = "rust1", since = "1.0.0")]
1726    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1727    #[inline]
1728    pub const fn abs(self) -> f32 {
1729        intrinsics::fabs(self)
1730    }
1731
1732    /// Returns a number that represents the sign of `self`.
1733    ///
1734    /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1735    /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1736    /// - NaN if the number is NaN
1737    ///
1738    /// # Examples
1739    ///
1740    /// ```
1741    /// let f = 3.5_f32;
1742    ///
1743    /// assert_eq!(f.signum(), 1.0);
1744    /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1745    ///
1746    /// assert!(f32::NAN.signum().is_nan());
1747    /// ```
1748    #[must_use = "method returns a new number and does not mutate the original value"]
1749    #[stable(feature = "rust1", since = "1.0.0")]
1750    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1751    #[inline]
1752    pub const fn signum(self) -> f32 {
1753        if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1754    }
1755
1756    /// Returns a number composed of the magnitude of `self` and the sign of
1757    /// `sign`.
1758    ///
1759    /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1760    /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1761    /// returned.
1762    ///
1763    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1764    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1765    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1766    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1767    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1768    /// info.
1769    ///
1770    /// # Examples
1771    ///
1772    /// ```
1773    /// let f = 3.5_f32;
1774    ///
1775    /// assert_eq!(f.copysign(0.42), 3.5_f32);
1776    /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1777    /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1778    /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1779    ///
1780    /// assert!(f32::NAN.copysign(1.0).is_nan());
1781    /// ```
1782    #[must_use = "method returns a new number and does not mutate the original value"]
1783    #[inline]
1784    #[stable(feature = "copysign", since = "1.35.0")]
1785    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1786    pub const fn copysign(self, sign: f32) -> f32 {
1787        intrinsics::copysignf32(self, sign)
1788    }
1789
1790    /// Float addition that allows optimizations based on algebraic rules.
1791    ///
1792    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1793    #[must_use = "method returns a new number and does not mutate the original value"]
1794    #[stable(feature = "float_algebraic", since = "1.98.0")]
1795    #[rustc_const_stable(feature = "float_algebraic", since = "1.98.0")]
1796    #[inline]
1797    pub const fn algebraic_add(self, rhs: f32) -> f32 {
1798        intrinsics::fadd_algebraic(self, rhs)
1799    }
1800
1801    /// Float subtraction that allows optimizations based on algebraic rules.
1802    ///
1803    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1804    #[must_use = "method returns a new number and does not mutate the original value"]
1805    #[stable(feature = "float_algebraic", since = "1.98.0")]
1806    #[rustc_const_stable(feature = "float_algebraic", since = "1.98.0")]
1807    #[inline]
1808    pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1809        intrinsics::fsub_algebraic(self, rhs)
1810    }
1811
1812    /// Float multiplication that allows optimizations based on algebraic rules.
1813    ///
1814    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1815    #[must_use = "method returns a new number and does not mutate the original value"]
1816    #[stable(feature = "float_algebraic", since = "1.98.0")]
1817    #[rustc_const_stable(feature = "float_algebraic", since = "1.98.0")]
1818    #[inline]
1819    pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1820        intrinsics::fmul_algebraic(self, rhs)
1821    }
1822
1823    /// Float division that allows optimizations based on algebraic rules.
1824    ///
1825    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1826    #[must_use = "method returns a new number and does not mutate the original value"]
1827    #[stable(feature = "float_algebraic", since = "1.98.0")]
1828    #[rustc_const_stable(feature = "float_algebraic", since = "1.98.0")]
1829    #[inline]
1830    pub const fn algebraic_div(self, rhs: f32) -> f32 {
1831        intrinsics::fdiv_algebraic(self, rhs)
1832    }
1833
1834    /// Float remainder that allows optimizations based on algebraic rules.
1835    ///
1836    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1837    #[must_use = "method returns a new number and does not mutate the original value"]
1838    #[stable(feature = "float_algebraic", since = "1.98.0")]
1839    #[rustc_const_stable(feature = "float_algebraic", since = "1.98.0")]
1840    #[inline]
1841    pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1842        intrinsics::frem_algebraic(self, rhs)
1843    }
1844
1845    /// Returns `self` if the value is not NaN, otherwise returns `replacement`
1846    /// if `self` is NaN.
1847    ///
1848    /// # Examples
1849    ///
1850    /// ```
1851    /// #![feature(float_nan_to)]
1852    ///
1853    /// let n = f32::NAN;
1854    /// let x = 2.0f32;
1855    /// let y = f32::INFINITY;
1856    ///
1857    /// assert_eq!(n.nan_to(0.0f32), 0.0f32);
1858    /// assert_eq!(x.nan_to(0.0f32), 2.0f32);
1859    /// assert_eq!(y.nan_to(0.0f32), f32::INFINITY);
1860    /// ```
1861    #[must_use = "method returns a new float and does not mutate the original value"]
1862    #[unstable(feature = "float_nan_to", issue = "161248")]
1863    #[rustc_const_unstable(feature = "float_nan_to", issue = "161248")]
1864    #[inline]
1865    pub const fn nan_to(self, replacement: f32) -> f32 {
1866        if self.is_nan() { replacement } else { self }
1867    }
1868}
1869
1870/// Experimental implementations of floating point functions in `core`.
1871///
1872/// _The standalone functions in this module are for testing only.
1873/// They will be stabilized as inherent methods._
1874#[unstable(feature = "core_float_math", issue = "137578")]
1875pub mod math {
1876    use crate::intrinsics;
1877    use crate::num::imp::libm;
1878
1879    /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1880    ///
1881    /// # Examples
1882    ///
1883    /// ```
1884    /// #![feature(core_float_math)]
1885    ///
1886    /// use core::f32;
1887    ///
1888    /// let f = 3.7_f32;
1889    /// let g = 3.0_f32;
1890    /// let h = -3.7_f32;
1891    ///
1892    /// assert_eq!(f32::math::floor(f), 3.0);
1893    /// assert_eq!(f32::math::floor(g), 3.0);
1894    /// assert_eq!(f32::math::floor(h), -4.0);
1895    /// ```
1896    ///
1897    /// _This standalone function is for testing only.
1898    /// It will be stabilized as an inherent method._
1899    ///
1900    /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1901    #[inline]
1902    #[unstable(feature = "core_float_math", issue = "137578")]
1903    #[must_use = "method returns a new number and does not mutate the original value"]
1904    pub const fn floor(x: f32) -> f32 {
1905        intrinsics::floorf32(x)
1906    }
1907
1908    /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1909    ///
1910    /// # Examples
1911    ///
1912    /// ```
1913    /// #![feature(core_float_math)]
1914    ///
1915    /// use core::f32;
1916    ///
1917    /// let f = 3.01_f32;
1918    /// let g = 4.0_f32;
1919    ///
1920    /// assert_eq!(f32::math::ceil(f), 4.0);
1921    /// assert_eq!(f32::math::ceil(g), 4.0);
1922    /// ```
1923    ///
1924    /// _This standalone function is for testing only.
1925    /// It will be stabilized as an inherent method._
1926    ///
1927    /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1928    #[inline]
1929    #[doc(alias = "ceiling")]
1930    #[must_use = "method returns a new number and does not mutate the original value"]
1931    #[unstable(feature = "core_float_math", issue = "137578")]
1932    pub const fn ceil(x: f32) -> f32 {
1933        intrinsics::ceilf32(x)
1934    }
1935
1936    /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1937    ///
1938    /// # Examples
1939    ///
1940    /// ```
1941    /// #![feature(core_float_math)]
1942    ///
1943    /// use core::f32;
1944    ///
1945    /// let f = 3.3_f32;
1946    /// let g = -3.3_f32;
1947    /// let h = -3.7_f32;
1948    /// let i = 3.5_f32;
1949    /// let j = 4.5_f32;
1950    ///
1951    /// assert_eq!(f32::math::round(f), 3.0);
1952    /// assert_eq!(f32::math::round(g), -3.0);
1953    /// assert_eq!(f32::math::round(h), -4.0);
1954    /// assert_eq!(f32::math::round(i), 4.0);
1955    /// assert_eq!(f32::math::round(j), 5.0);
1956    /// ```
1957    ///
1958    /// _This standalone function is for testing only.
1959    /// It will be stabilized as an inherent method._
1960    ///
1961    /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
1962    #[inline]
1963    #[unstable(feature = "core_float_math", issue = "137578")]
1964    #[must_use = "method returns a new number and does not mutate the original value"]
1965    pub const fn round(x: f32) -> f32 {
1966        intrinsics::roundf32(x)
1967    }
1968
1969    /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
1970    /// details.
1971    ///
1972    /// # Examples
1973    ///
1974    /// ```
1975    /// #![feature(core_float_math)]
1976    ///
1977    /// use core::f32;
1978    ///
1979    /// let f = 3.3_f32;
1980    /// let g = -3.3_f32;
1981    /// let h = 3.5_f32;
1982    /// let i = 4.5_f32;
1983    ///
1984    /// assert_eq!(f32::math::round_ties_even(f), 3.0);
1985    /// assert_eq!(f32::math::round_ties_even(g), -3.0);
1986    /// assert_eq!(f32::math::round_ties_even(h), 4.0);
1987    /// assert_eq!(f32::math::round_ties_even(i), 4.0);
1988    /// ```
1989    ///
1990    /// _This standalone function is for testing only.
1991    /// It will be stabilized as an inherent method._
1992    ///
1993    /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
1994    #[inline]
1995    #[unstable(feature = "core_float_math", issue = "137578")]
1996    #[must_use = "method returns a new number and does not mutate the original value"]
1997    pub const fn round_ties_even(x: f32) -> f32 {
1998        intrinsics::round_ties_even_f32(x)
1999    }
2000
2001    /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
2002    ///
2003    /// # Examples
2004    ///
2005    /// ```
2006    /// #![feature(core_float_math)]
2007    ///
2008    /// use core::f32;
2009    ///
2010    /// let f = 3.7_f32;
2011    /// let g = 3.0_f32;
2012    /// let h = -3.7_f32;
2013    ///
2014    /// assert_eq!(f32::math::trunc(f), 3.0);
2015    /// assert_eq!(f32::math::trunc(g), 3.0);
2016    /// assert_eq!(f32::math::trunc(h), -3.0);
2017    /// ```
2018    ///
2019    /// _This standalone function is for testing only.
2020    /// It will be stabilized as an inherent method._
2021    ///
2022    /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
2023    #[inline]
2024    #[doc(alias = "truncate")]
2025    #[must_use = "method returns a new number and does not mutate the original value"]
2026    #[unstable(feature = "core_float_math", issue = "137578")]
2027    pub const fn trunc(x: f32) -> f32 {
2028        intrinsics::truncf32(x)
2029    }
2030
2031    /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
2032    ///
2033    /// # Examples
2034    ///
2035    /// ```
2036    /// #![feature(core_float_math)]
2037    ///
2038    /// use core::f32;
2039    ///
2040    /// let x = 3.6_f32;
2041    /// let y = -3.6_f32;
2042    /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
2043    /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
2044    ///
2045    /// assert!(abs_difference_x <= f32::EPSILON);
2046    /// assert!(abs_difference_y <= f32::EPSILON);
2047    /// ```
2048    ///
2049    /// _This standalone function is for testing only.
2050    /// It will be stabilized as an inherent method._
2051    ///
2052    /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
2053    #[inline]
2054    #[unstable(feature = "core_float_math", issue = "137578")]
2055    #[must_use = "method returns a new number and does not mutate the original value"]
2056    pub const fn fract(x: f32) -> f32 {
2057        x - trunc(x)
2058    }
2059
2060    /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
2061    ///
2062    /// # Examples
2063    ///
2064    /// ```
2065    /// # #![allow(unused_features)]
2066    /// #![feature(core_float_math)]
2067    ///
2068    /// # // FIXME(#140515): mingw has an incorrect fma
2069    /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
2070    /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
2071    /// use core::f32;
2072    ///
2073    /// let m = 10.0_f32;
2074    /// let x = 4.0_f32;
2075    /// let b = 60.0_f32;
2076    ///
2077    /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
2078    /// assert_eq!(m * x + b, 100.0);
2079    ///
2080    /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
2081    /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
2082    /// let minus_one = -1.0_f32;
2083    ///
2084    /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
2085    /// assert_eq!(
2086    ///     f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
2087    ///     -f32::EPSILON * f32::EPSILON
2088    /// );
2089    /// // Different rounding with the non-fused multiply and add.
2090    /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
2091    /// # }
2092    /// ```
2093    ///
2094    /// _This standalone function is for testing only.
2095    /// It will be stabilized as an inherent method._
2096    ///
2097    /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
2098    #[inline]
2099    #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
2100    #[must_use = "method returns a new number and does not mutate the original value"]
2101    #[unstable(feature = "core_float_math", issue = "137578")]
2102    pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
2103        intrinsics::fmaf32(x, y, z)
2104    }
2105
2106    /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
2107    ///
2108    /// # Examples
2109    ///
2110    /// ```
2111    /// #![feature(core_float_math)]
2112    ///
2113    /// use core::f32;
2114    ///
2115    /// let a: f32 = 7.0;
2116    /// let b = 4.0;
2117    /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
2118    /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
2119    /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
2120    /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
2121    /// ```
2122    ///
2123    /// _This standalone function is for testing only.
2124    /// It will be stabilized as an inherent method._
2125    ///
2126    /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
2127    #[inline]
2128    #[unstable(feature = "core_float_math", issue = "137578")]
2129    #[must_use = "method returns a new number and does not mutate the original value"]
2130    pub fn div_euclid(x: f32, rhs: f32) -> f32 {
2131        let q = trunc(x / rhs);
2132        if x % rhs < 0.0 {
2133            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
2134        }
2135        q
2136    }
2137
2138    /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
2139    ///
2140    /// # Examples
2141    ///
2142    /// ```
2143    /// #![feature(core_float_math)]
2144    ///
2145    /// use core::f32;
2146    ///
2147    /// let a: f32 = 7.0;
2148    /// let b = 4.0;
2149    /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
2150    /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
2151    /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
2152    /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
2153    /// // limitation due to round-off error
2154    /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
2155    /// ```
2156    ///
2157    /// _This standalone function is for testing only.
2158    /// It will be stabilized as an inherent method._
2159    ///
2160    /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
2161    #[inline]
2162    #[doc(alias = "modulo", alias = "mod")]
2163    #[unstable(feature = "core_float_math", issue = "137578")]
2164    #[must_use = "method returns a new number and does not mutate the original value"]
2165    pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
2166        let r = x % rhs;
2167        if r < 0.0 { r + rhs.abs() } else { r }
2168    }
2169
2170    /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
2171    ///
2172    /// # Examples
2173    ///
2174    /// ```
2175    /// #![feature(core_float_math)]
2176    ///
2177    /// use core::f32;
2178    ///
2179    /// let x = 2.0_f32;
2180    /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
2181    /// assert!(abs_difference <= 1e-5);
2182    ///
2183    /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
2184    /// ```
2185    ///
2186    /// _This standalone function is for testing only.
2187    /// It will be stabilized as an inherent method._
2188    ///
2189    /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
2190    #[inline]
2191    #[must_use = "method returns a new number and does not mutate the original value"]
2192    #[unstable(feature = "core_float_math", issue = "137578")]
2193    pub fn powi(x: f32, n: i32) -> f32 {
2194        intrinsics::powif32(x, n)
2195    }
2196
2197    /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
2198    ///
2199    /// # Examples
2200    ///
2201    /// ```
2202    /// #![feature(core_float_math)]
2203    ///
2204    /// use core::f32;
2205    ///
2206    /// let positive = 4.0_f32;
2207    /// let negative = -4.0_f32;
2208    /// let negative_zero = -0.0_f32;
2209    ///
2210    /// assert_eq!(f32::math::sqrt(positive), 2.0);
2211    /// assert!(f32::math::sqrt(negative).is_nan());
2212    /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
2213    /// ```
2214    ///
2215    /// _This standalone function is for testing only.
2216    /// It will be stabilized as an inherent method._
2217    ///
2218    /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
2219    #[inline]
2220    #[doc(alias = "squareRoot")]
2221    #[unstable(feature = "core_float_math", issue = "137578")]
2222    #[must_use = "method returns a new number and does not mutate the original value"]
2223    pub fn sqrt(x: f32) -> f32 {
2224        intrinsics::sqrtf32(x)
2225    }
2226
2227    /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
2228    ///
2229    /// # Examples
2230    ///
2231    /// ```
2232    /// #![feature(core_float_math)]
2233    ///
2234    /// use core::f32;
2235    ///
2236    /// let x = 3.0f32;
2237    /// let y = -3.0f32;
2238    ///
2239    /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
2240    /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
2241    ///
2242    /// assert!(abs_difference_x <= 1e-6);
2243    /// assert!(abs_difference_y <= 1e-6);
2244    /// ```
2245    ///
2246    /// _This standalone function is for testing only.
2247    /// It will be stabilized as an inherent method._
2248    ///
2249    /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
2250    #[inline]
2251    #[stable(feature = "rust1", since = "1.0.0")]
2252    #[deprecated(
2253        since = "1.10.0",
2254        note = "you probably meant `(self - other).abs()`: \
2255            this operation is `(self - other).max(0.0)` \
2256            except that `abs_sub` also propagates NaNs (also \
2257            known as `fdimf` in C). If you truly need the positive \
2258            difference, consider using that expression or the C function \
2259            `fdimf`, depending on how you wish to handle NaN (please consider \
2260            filing an issue describing your use-case too)."
2261    )]
2262    #[must_use = "method returns a new number and does not mutate the original value"]
2263    pub fn abs_sub(x: f32, other: f32) -> f32 {
2264        libm::fdimf(x, other)
2265    }
2266
2267    /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2268    ///
2269    /// # Unspecified precision
2270    ///
2271    /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2272    /// can even differ within the same execution from one invocation to the next.
2273    /// This function currently corresponds to the `cbrtf` from libc on Unix
2274    /// and Windows. Note that this might change in the future.
2275    ///
2276    /// # Examples
2277    ///
2278    /// ```
2279    /// #![feature(core_float_math)]
2280    ///
2281    /// use core::f32;
2282    ///
2283    /// let x = 8.0f32;
2284    ///
2285    /// // x^(1/3) - 2 == 0
2286    /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2287    ///
2288    /// assert!(abs_difference <= 1e-6);
2289    /// ```
2290    ///
2291    /// _This standalone function is for testing only.
2292    /// It will be stabilized as an inherent method._
2293    ///
2294    /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2295    #[inline]
2296    #[must_use = "method returns a new number and does not mutate the original value"]
2297    #[unstable(feature = "core_float_math", issue = "137578")]
2298    pub fn cbrt(x: f32) -> f32 {
2299        libm::cbrtf(x)
2300    }
2301}