src/libcore/num/f32.rs

   1 //! This module provides constants which are specific to the implementation
   2 //! of the `f32` floating point data type.
   3 //!
   4 //! *[See also the `f32` primitive type](../../std/primitive.f32.html).*
   5 //!
   6 //! Mathematically significant numbers are provided in the `consts` sub-module.
   7
   8 #![stable(feature = "rust1", since = "1.0.0")]
   9
  10 #[cfg(not(bootstrap))]
  11 use crate::convert::FloatToInt;
  12 #[cfg(not(test))]
  13 use crate::intrinsics;
  14 use crate::mem;
  15 use crate::num::FpCategory;
  16
  17 /// The radix or base of the internal representation of `f32`.
  18 #[stable(feature = "rust1", since = "1.0.0")]
  19 pub const RADIX: u32 = 2;
  20
  21 /// Number of significant digits in base 2.
  22 #[stable(feature = "rust1", since = "1.0.0")]
  23 pub const MANTISSA_DIGITS: u32 = 24;
  24 /// Approximate number of significant digits in base 10.
  25 #[stable(feature = "rust1", since = "1.0.0")]
  26 pub const DIGITS: u32 = 6;
  27
  28 /// [Machine epsilon] value for `f32`.
  29 ///
  30 /// This is the difference between `1.0` and the next larger representable number.
  31 ///
  32 /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
  33 #[stable(feature = "rust1", since = "1.0.0")]
  34 pub const EPSILON: f32 = 1.19209290e-07_f32;
  35
  36 /// Smallest finite `f32` value.
  37 #[stable(feature = "rust1", since = "1.0.0")]
  38 pub const MIN: f32 = -3.40282347e+38_f32;
  39 /// Smallest positive normal `f32` value.
  40 #[stable(feature = "rust1", since = "1.0.0")]
  41 pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
  42 /// Largest finite `f32` value.
  43 #[stable(feature = "rust1", since = "1.0.0")]
  44 pub const MAX: f32 = 3.40282347e+38_f32;
  45
  46 /// One greater than the minimum possible normal power of 2 exponent.
  47 #[stable(feature = "rust1", since = "1.0.0")]
  48 pub const MIN_EXP: i32 = -125;
  49 /// Maximum possible power of 2 exponent.
  50 #[stable(feature = "rust1", since = "1.0.0")]
  51 pub const MAX_EXP: i32 = 128;
  52
  53 /// Minimum possible normal power of 10 exponent.
  54 #[stable(feature = "rust1", since = "1.0.0")]
  55 pub const MIN_10_EXP: i32 = -37;
  56 /// Maximum possible power of 10 exponent.
  57 #[stable(feature = "rust1", since = "1.0.0")]
  58 pub const MAX_10_EXP: i32 = 38;
  59
  60 /// Not a Number (NaN).
  61 #[stable(feature = "rust1", since = "1.0.0")]
  62 pub const NAN: f32 = 0.0_f32 / 0.0_f32;
  63 /// Infinity (∞).
  64 #[stable(feature = "rust1", since = "1.0.0")]
  65 pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
  66 /// Negative infinity (-∞).
  67 #[stable(feature = "rust1", since = "1.0.0")]
  68 pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
  69
  70 /// Basic mathematical constants.
  71 #[stable(feature = "rust1", since = "1.0.0")]
  72 pub mod consts {
  73     // FIXME: replace with mathematical constants from cmath.
  74
  75     /// Archimedes' constant (π)
  76     #[stable(feature = "rust1", since = "1.0.0")]
  77     pub const PI: f32 = 3.14159265358979323846264338327950288_f32;
  78
  79     /// The full circle constant (τ)
  80     ///
  81     /// Equal to 2π.
  82     #[unstable(feature = "tau_constant", issue = "66770")]
  83     pub const TAU: f32 = 6.28318530717958647692528676655900577_f32;
  84
  85     /// π/2
  86     #[stable(feature = "rust1", since = "1.0.0")]
  87     pub const FRAC_PI_2: f32 = 1.57079632679489661923132169163975144_f32;
  88
  89     /// π/3
  90     #[stable(feature = "rust1", since = "1.0.0")]
  91     pub const FRAC_PI_3: f32 = 1.04719755119659774615421446109316763_f32;
  92
  93     /// π/4
  94     #[stable(feature = "rust1", since = "1.0.0")]
  95     pub const FRAC_PI_4: f32 = 0.785398163397448309615660845819875721_f32;
  96
  97     /// π/6
  98     #[stable(feature = "rust1", since = "1.0.0")]
  99     pub const FRAC_PI_6: f32 = 0.52359877559829887307710723054658381_f32;
 100
 101     /// π/8
 102     #[stable(feature = "rust1", since = "1.0.0")]
 103     pub const FRAC_PI_8: f32 = 0.39269908169872415480783042290993786_f32;
 104
 105     /// 1/π
 106     #[stable(feature = "rust1", since = "1.0.0")]
 107     pub const FRAC_1_PI: f32 = 0.318309886183790671537767526745028724_f32;
 108
 109     /// 2/π
 110     #[stable(feature = "rust1", since = "1.0.0")]
 111     pub const FRAC_2_PI: f32 = 0.636619772367581343075535053490057448_f32;
 112
 113     /// 2/sqrt(π)
 114     #[stable(feature = "rust1", since = "1.0.0")]
 115     pub const FRAC_2_SQRT_PI: f32 = 1.12837916709551257389615890312154517_f32;
 116
 117     /// sqrt(2)
 118     #[stable(feature = "rust1", since = "1.0.0")]
 119     pub const SQRT_2: f32 = 1.41421356237309504880168872420969808_f32;
 120
 121     /// 1/sqrt(2)
 122     #[stable(feature = "rust1", since = "1.0.0")]
 123     pub const FRAC_1_SQRT_2: f32 = 0.707106781186547524400844362104849039_f32;
 124
 125     /// Euler's number (e)
 126     #[stable(feature = "rust1", since = "1.0.0")]
 127     pub const E: f32 = 2.71828182845904523536028747135266250_f32;
 128
 129     /// log<sub>2</sub>(e)
 130     #[stable(feature = "rust1", since = "1.0.0")]
 131     pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
 132
 133     /// log<sub>2</sub>(10)
 134     #[unstable(feature = "extra_log_consts", issue = "50540")]
 135     pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
 136
 137     /// log<sub>10</sub>(e)
 138     #[stable(feature = "rust1", since = "1.0.0")]
 139     pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
 140
 141     /// log<sub>10</sub>(2)
 142     #[unstable(feature = "extra_log_consts", issue = "50540")]
 143     pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
 144
 145     /// ln(2)
 146     #[stable(feature = "rust1", since = "1.0.0")]
 147     pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
 148
 149     /// ln(10)
 150     #[stable(feature = "rust1", since = "1.0.0")]
 151     pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
 152 }
 153
 154 #[lang = "f32"]
 155 #[cfg(not(test))]
 156 impl f32 {
 157     /// Returns `true` if this value is `NaN`.
 158     ///
 159     /// ```
 160     /// use std::f32;
 161     ///
 162     /// let nan = f32::NAN;
 163     /// let f = 7.0_f32;
 164     ///
 165     /// assert!(nan.is_nan());
 166     /// assert!(!f.is_nan());
 167     /// ```
 168     #[stable(feature = "rust1", since = "1.0.0")]
 169     #[inline]
 170     pub fn is_nan(self) -> bool {
 171         self != self
 172     }
 173
 174     // FIXME(#50145): `abs` is publicly unavailable in libcore due to
 175     // concerns about portability, so this implementation is for
 176     // private use internally.
 177     #[inline]
 178     fn abs_private(self) -> f32 {
 179         f32::from_bits(self.to_bits() & 0x7fff_ffff)
 180     }
 181
 182     /// Returns `true` if this value is positive infinity or negative infinity, and
 183     /// `false` otherwise.
 184     ///
 185     /// ```
 186     /// use std::f32;
 187     ///
 188     /// let f = 7.0f32;
 189     /// let inf = f32::INFINITY;
 190     /// let neg_inf = f32::NEG_INFINITY;
 191     /// let nan = f32::NAN;
 192     ///
 193     /// assert!(!f.is_infinite());
 194     /// assert!(!nan.is_infinite());
 195     ///
 196     /// assert!(inf.is_infinite());
 197     /// assert!(neg_inf.is_infinite());
 198     /// ```
 199     #[stable(feature = "rust1", since = "1.0.0")]
 200     #[inline]
 201     pub fn is_infinite(self) -> bool {
 202         self.abs_private() == INFINITY
 203     }
 204
 205     /// Returns `true` if this number is neither infinite nor `NaN`.
 206     ///
 207     /// ```
 208     /// use std::f32;
 209     ///
 210     /// let f = 7.0f32;
 211     /// let inf = f32::INFINITY;
 212     /// let neg_inf = f32::NEG_INFINITY;
 213     /// let nan = f32::NAN;
 214     ///
 215     /// assert!(f.is_finite());
 216     ///
 217     /// assert!(!nan.is_finite());
 218     /// assert!(!inf.is_finite());
 219     /// assert!(!neg_inf.is_finite());
 220     /// ```
 221     #[stable(feature = "rust1", since = "1.0.0")]
 222     #[inline]
 223     pub fn is_finite(self) -> bool {
 224         // There's no need to handle NaN separately: if self is NaN,
 225         // the comparison is not true, exactly as desired.
 226         self.abs_private() < INFINITY
 227     }
 228
 229     /// Returns `true` if the number is neither zero, infinite,
 230     /// [subnormal][subnormal], or `NaN`.
 231     ///
 232     /// ```
 233     /// use std::f32;
 234     ///
 235     /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
 236     /// let max = f32::MAX;
 237     /// let lower_than_min = 1.0e-40_f32;
 238     /// let zero = 0.0_f32;
 239     ///
 240     /// assert!(min.is_normal());
 241     /// assert!(max.is_normal());
 242     ///
 243     /// assert!(!zero.is_normal());
 244     /// assert!(!f32::NAN.is_normal());
 245     /// assert!(!f32::INFINITY.is_normal());
 246     /// // Values between `0` and `min` are Subnormal.
 247     /// assert!(!lower_than_min.is_normal());
 248     /// ```
 249     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
 250     #[stable(feature = "rust1", since = "1.0.0")]
 251     #[inline]
 252     pub fn is_normal(self) -> bool {
 253         self.classify() == FpCategory::Normal
 254     }
 255
 256     /// Returns the floating point category of the number. If only one property
 257     /// is going to be tested, it is generally faster to use the specific
 258     /// predicate instead.
 259     ///
 260     /// ```
 261     /// use std::num::FpCategory;
 262     /// use std::f32;
 263     ///
 264     /// let num = 12.4_f32;
 265     /// let inf = f32::INFINITY;
 266     ///
 267     /// assert_eq!(num.classify(), FpCategory::Normal);
 268     /// assert_eq!(inf.classify(), FpCategory::Infinite);
 269     /// ```
 270     #[stable(feature = "rust1", since = "1.0.0")]
 271     pub fn classify(self) -> FpCategory {
 272         const EXP_MASK: u32 = 0x7f800000;
 273         const MAN_MASK: u32 = 0x007fffff;
 274
 275         let bits = self.to_bits();
 276         match (bits & MAN_MASK, bits & EXP_MASK) {
 277             (0, 0) => FpCategory::Zero,
 278             (_, 0) => FpCategory::Subnormal,
 279             (0, EXP_MASK) => FpCategory::Infinite,
 280             (_, EXP_MASK) => FpCategory::Nan,
 281             _ => FpCategory::Normal,
 282         }
 283     }
 284
 285     /// Returns `true` if `self` has a positive sign, including `+0.0`, `NaN`s with
 286     /// positive sign bit and positive infinity.
 287     ///
 288     /// ```
 289     /// let f = 7.0_f32;
 290     /// let g = -7.0_f32;
 291     ///
 292     /// assert!(f.is_sign_positive());
 293     /// assert!(!g.is_sign_positive());
 294     /// ```
 295     #[stable(feature = "rust1", since = "1.0.0")]
 296     #[inline]
 297     pub fn is_sign_positive(self) -> bool {
 298         !self.is_sign_negative()
 299     }
 300
 301     /// Returns `true` if `self` has a negative sign, including `-0.0`, `NaN`s with
 302     /// negative sign bit and negative infinity.
 303     ///
 304     /// ```
 305     /// let f = 7.0f32;
 306     /// let g = -7.0f32;
 307     ///
 308     /// assert!(!f.is_sign_negative());
 309     /// assert!(g.is_sign_negative());
 310     /// ```
 311     #[stable(feature = "rust1", since = "1.0.0")]
 312     #[inline]
 313     pub fn is_sign_negative(self) -> bool {
 314         // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
 315         // applies to zeros and NaNs as well.
 316         self.to_bits() & 0x8000_0000 != 0
 317     }
 318
 319     /// Takes the reciprocal (inverse) of a number, `1/x`.
 320     ///
 321     /// ```
 322     /// use std::f32;
 323     ///
 324     /// let x = 2.0_f32;
 325     /// let abs_difference = (x.recip() - (1.0 / x)).abs();
 326     ///
 327     /// assert!(abs_difference <= f32::EPSILON);
 328     /// ```
 329     #[stable(feature = "rust1", since = "1.0.0")]
 330     #[inline]
 331     pub fn recip(self) -> f32 {
 332         1.0 / self
 333     }
 334
 335     /// Converts radians to degrees.
 336     ///
 337     /// ```
 338     /// use std::f32::{self, consts};
 339     ///
 340     /// let angle = consts::PI;
 341     ///
 342     /// let abs_difference = (angle.to_degrees() - 180.0).abs();
 343     ///
 344     /// assert!(abs_difference <= f32::EPSILON);
 345     /// ```
 346     #[stable(feature = "f32_deg_rad_conversions", since="1.7.0")]
 347     #[inline]
 348     pub fn to_degrees(self) -> f32 {
 349         // Use a constant for better precision.
 350         const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
 351         self * PIS_IN_180
 352     }
 353
 354     /// Converts degrees to radians.
 355     ///
 356     /// ```
 357     /// use std::f32::{self, consts};
 358     ///
 359     /// let angle = 180.0f32;
 360     ///
 361     /// let abs_difference = (angle.to_radians() - consts::PI).abs();
 362     ///
 363     /// assert!(abs_difference <= f32::EPSILON);
 364     /// ```
 365     #[stable(feature = "f32_deg_rad_conversions", since="1.7.0")]
 366     #[inline]
 367     pub fn to_radians(self) -> f32 {
 368         let value: f32 = consts::PI;
 369         self * (value / 180.0f32)
 370     }
 371
 372     /// Returns the maximum of the two numbers.
 373     ///
 374     /// ```
 375     /// let x = 1.0f32;
 376     /// let y = 2.0f32;
 377     ///
 378     /// assert_eq!(x.max(y), y);
 379     /// ```
 380     ///
 381     /// If one of the arguments is NaN, then the other argument is returned.
 382     #[stable(feature = "rust1", since = "1.0.0")]
 383     #[inline]
 384     pub fn max(self, other: f32) -> f32 {
 385         intrinsics::maxnumf32(self, other)
 386     }
 387
 388     /// Returns the minimum of the two numbers.
 389     ///
 390     /// ```
 391     /// let x = 1.0f32;
 392     /// let y = 2.0f32;
 393     ///
 394     /// assert_eq!(x.min(y), x);
 395     /// ```
 396     ///
 397     /// If one of the arguments is NaN, then the other argument is returned.
 398     #[stable(feature = "rust1", since = "1.0.0")]
 399     #[inline]
 400     pub fn min(self, other: f32) -> f32 {
 401         intrinsics::minnumf32(self, other)
 402     }
 403
 404     /// Rounds toward zero and converts to any primitive integer type,
 405     /// assuming that the value is finite and fits in that type.
 406     ///
 407     /// ```
 408     /// #![feature(float_approx_unchecked_to)]
 409     ///
 410     /// let value = 4.6_f32;
 411     /// let rounded = unsafe { value.approx_unchecked_to::<u16>() };
 412     /// assert_eq!(rounded, 4);
 413     ///
 414     /// let value = -128.9_f32;
 415     /// let rounded = unsafe { value.approx_unchecked_to::<i8>() };
 416     /// assert_eq!(rounded, std::i8::MIN);
 417     /// ```
 418     ///
 419     /// # Safety
 420     ///
 421     /// The value must:
 422     ///
 423     /// * Not be `NaN`
 424     /// * Not be infinite
 425     /// * Be representable in the return type `Int`, after truncating off its fractional part
 426     #[cfg(not(bootstrap))]
 427     #[unstable(feature = "float_approx_unchecked_to", issue = "67058")]
 428     #[inline]
 429     pub unsafe fn approx_unchecked_to<Int>(self) -> Int where Self: FloatToInt<Int> {
 430         FloatToInt::<Int>::approx_unchecked(self)
 431     }
 432
 433     /// Raw transmutation to `u32`.
 434     ///
 435     /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
 436     ///
 437     /// See `from_bits` for some discussion of the portability of this operation
 438     /// (there are almost no issues).
 439     ///
 440     /// Note that this function is distinct from `as` casting, which attempts to
 441     /// preserve the *numeric* value, and not the bitwise value.
 442     ///
 443     /// # Examples
 444     ///
 445     /// ```
 446     /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
 447     /// assert_eq!((12.5f32).to_bits(), 0x41480000);
 448     ///
 449     /// ```
 450     #[stable(feature = "float_bits_conv", since = "1.20.0")]
 451     #[inline]
 452     pub fn to_bits(self) -> u32 {
 453         // SAFETY: `u32` is a plain old datatype so we can always transmute to it
 454         unsafe { mem::transmute(self) }
 455     }
 456
 457     /// Raw transmutation from `u32`.
 458     ///
 459     /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
 460     /// It turns out this is incredibly portable, for two reasons:
 461     ///
 462     /// * Floats and Ints have the same endianness on all supported platforms.
 463     /// * IEEE-754 very precisely specifies the bit layout of floats.
 464     ///
 465     /// However there is one caveat: prior to the 2008 version of IEEE-754, how
 466     /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
 467     /// (notably x86 and ARM) picked the interpretation that was ultimately
 468     /// standardized in 2008, but some didn't (notably MIPS). As a result, all
 469     /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
 470     ///
 471     /// Rather than trying to preserve signaling-ness cross-platform, this
 472     /// implementation favors preserving the exact bits. This means that
 473     /// any payloads encoded in NaNs will be preserved even if the result of
 474     /// this method is sent over the network from an x86 machine to a MIPS one.
 475     ///
 476     /// If the results of this method are only manipulated by the same
 477     /// architecture that produced them, then there is no portability concern.
 478     ///
 479     /// If the input isn't NaN, then there is no portability concern.
 480     ///
 481     /// If you don't care about signalingness (very likely), then there is no
 482     /// portability concern.
 483     ///
 484     /// Note that this function is distinct from `as` casting, which attempts to
 485     /// preserve the *numeric* value, and not the bitwise value.
 486     ///
 487     /// # Examples
 488     ///
 489     /// ```
 490     /// let v = f32::from_bits(0x41480000);
 491     /// assert_eq!(v, 12.5);
 492     /// ```
 493     #[stable(feature = "float_bits_conv", since = "1.20.0")]
 494     #[inline]
 495     pub fn from_bits(v: u32) -> Self {
 496         // SAFETY: `u32` is a plain old datatype so we can always transmute from it
 497         // It turns out the safety issues with sNaN were overblown! Hooray!
 498         unsafe { mem::transmute(v) }
 499     }
 500
 501     /// Return the memory representation of this floating point number as a byte array in
 502     /// big-endian (network) byte order.
 503     ///
 504     /// # Examples
 505     ///
 506     /// ```
 507     /// let bytes = 12.5f32.to_be_bytes();
 508     /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
 509     /// ```
 510     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
 511     #[inline]
 512     pub fn to_be_bytes(self) -> [u8; 4] {
 513         self.to_bits().to_be_bytes()
 514     }
 515
 516     /// Return the memory representation of this floating point number as a byte array in
 517     /// little-endian byte order.
 518     ///
 519     /// # Examples
 520     ///
 521     /// ```
 522     /// let bytes = 12.5f32.to_le_bytes();
 523     /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
 524     /// ```
 525     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
 526     #[inline]
 527     pub fn to_le_bytes(self) -> [u8; 4] {
 528         self.to_bits().to_le_bytes()
 529     }
 530
 531     /// Return the memory representation of this floating point number as a byte array in
 532     /// native byte order.
 533     ///
 534     /// As the target platform's native endianness is used, portable code
 535     /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
 536     ///
 537     /// [`to_be_bytes`]: #method.to_be_bytes
 538     /// [`to_le_bytes`]: #method.to_le_bytes
 539     ///
 540     /// # Examples
 541     ///
 542     /// ```
 543     /// let bytes = 12.5f32.to_ne_bytes();
 544     /// assert_eq!(
 545     ///     bytes,
 546     ///     if cfg!(target_endian = "big") {
 547     ///         [0x41, 0x48, 0x00, 0x00]
 548     ///     } else {
 549     ///         [0x00, 0x00, 0x48, 0x41]
 550     ///     }
 551     /// );
 552     /// ```
 553     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
 554     #[inline]
 555     pub fn to_ne_bytes(self) -> [u8; 4] {
 556         self.to_bits().to_ne_bytes()
 557     }
 558
 559     /// Create a floating point value from its representation as a byte array in big endian.
 560     ///
 561     /// # Examples
 562     ///
 563     /// ```
 564     /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
 565     /// assert_eq!(value, 12.5);
 566     /// ```
 567     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
 568     #[inline]
 569     pub fn from_be_bytes(bytes: [u8; 4]) -> Self {
 570         Self::from_bits(u32::from_be_bytes(bytes))
 571     }
 572
 573     /// Create a floating point value from its representation as a byte array in little endian.
 574     ///
 575     /// # Examples
 576     ///
 577     /// ```
 578     /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
 579     /// assert_eq!(value, 12.5);
 580     /// ```
 581     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
 582     #[inline]
 583     pub fn from_le_bytes(bytes: [u8; 4]) -> Self {
 584         Self::from_bits(u32::from_le_bytes(bytes))
 585     }
 586
 587     /// Create a floating point value from its representation as a byte array in native endian.
 588     ///
 589     /// As the target platform's native endianness is used, portable code
 590     /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
 591     /// appropriate instead.
 592     ///
 593     /// [`from_be_bytes`]: #method.from_be_bytes
 594     /// [`from_le_bytes`]: #method.from_le_bytes
 595     ///
 596     /// # Examples
 597     ///
 598     /// ```
 599     /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
 600     ///     [0x41, 0x48, 0x00, 0x00]
 601     /// } else {
 602     ///     [0x00, 0x00, 0x48, 0x41]
 603     /// });
 604     /// assert_eq!(value, 12.5);
 605     /// ```
 606     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
 607     #[inline]
 608     pub fn from_ne_bytes(bytes: [u8; 4]) -> Self {
 609         Self::from_bits(u32::from_ne_bytes(bytes))
 610     }
 611 }