A 32-bit floating point type (specifically, the "binary32" type defined in IEEE 754-2008).
This type can represent a wide range of decimal numbers, like 3.5
, 27
, -113.75
, 0.0078125
, 34359738368
, 0
, -1
. So unlike integer types (such as i32
), floating point types can represent non-integer numbers, too.
However, being able to represent this wide range of numbers comes at the cost of precision: floats can only represent some of the real numbers and calculation with floats round to a nearby representable number. For example, 5.0
and 1.0
can be exactly represented as f32
, but 1.0 / 5.0
results in 0.20000000298023223876953125
since 0.2
cannot be exactly represented as f32
. Note however, that printing floats with println
and friends will often discard insignificant digits: println!("{}", 1.0f32 / 5.0f32)
will print 0.2
.
Additionally, f32
can represent a couple of special values:
-0
: this is just due to how floats are encoded. It is semantically equivalent to 0
and -0.0 == 0.0
results in true
.1.0 / 0.0
.(-1.0).sqrt()
. NaN has some potentially unexpected behavior: it is unequal to any float, including itself! It is also neither smaller nor greater than any float, making it impossible to sort. Lastly, it is considered infectious as almost all calculations where one of the operands is NaN will also result in NaN.For more information on floating point numbers, see Wikipedia.
See also the std::f32::consts
module.
impl f32
[src]
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn floor(self) -> f32
[src]
Returns the largest integer less than or equal to a number.
let f = 3.7_f32; let g = 3.0_f32; let h = -3.7_f32; assert_eq!(f.floor(), 3.0); assert_eq!(g.floor(), 3.0); assert_eq!(h.floor(), -4.0);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn ceil(self) -> f32
[src]
Returns the smallest integer greater than or equal to a number.
let f = 3.01_f32; let g = 4.0_f32; assert_eq!(f.ceil(), 4.0); assert_eq!(g.ceil(), 4.0);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn round(self) -> f32
[src]
Returns the nearest integer to a number. Round half-way cases away from 0.0
.
let f = 3.3_f32; let g = -3.3_f32; assert_eq!(f.round(), 3.0); assert_eq!(g.round(), -3.0);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn trunc(self) -> f32
[src]
Returns the integer part of a number.
let f = 3.7_f32; let g = 3.0_f32; let h = -3.7_f32; assert_eq!(f.trunc(), 3.0); assert_eq!(g.trunc(), 3.0); assert_eq!(h.trunc(), -3.0);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn fract(self) -> f32
[src]
Returns the fractional part of a number.
let x = 3.6_f32; let y = -3.6_f32; let abs_difference_x = (x.fract() - 0.6).abs(); let abs_difference_y = (y.fract() - (-0.6)).abs(); assert!(abs_difference_x <= f32::EPSILON); assert!(abs_difference_y <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn abs(self) -> f32
[src]
Computes the absolute value of self
. Returns NAN
if the number is NAN
.
let x = 3.5_f32; let y = -3.5_f32; let abs_difference_x = (x.abs() - x).abs(); let abs_difference_y = (y.abs() - (-y)).abs(); assert!(abs_difference_x <= f32::EPSILON); assert!(abs_difference_y <= f32::EPSILON); assert!(f32::NAN.abs().is_nan());
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn signum(self) -> f32
[src]
Returns a number that represents the sign of self
.
1.0
if the number is positive, +0.0
or INFINITY
-1.0
if the number is negative, -0.0
or NEG_INFINITY
NAN
if the number is NAN
let f = 3.5_f32; assert_eq!(f.signum(), 1.0); assert_eq!(f32::NEG_INFINITY.signum(), -1.0); assert!(f32::NAN.signum().is_nan());
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn copysign(self, sign: f32) -> f32
[src]1.35.0
Returns a number composed of the magnitude of self
and the sign of sign
.
Equal to self
if the sign of self
and sign
are the same, otherwise equal to -self
. If self
is a NAN
, then a NAN
with the sign of sign
is returned.
let f = 3.5_f32; assert_eq!(f.copysign(0.42), 3.5_f32); assert_eq!(f.copysign(-0.42), -3.5_f32); assert_eq!((-f).copysign(0.42), 3.5_f32); assert_eq!((-f).copysign(-0.42), -3.5_f32); assert!(f32::NAN.copysign(1.0).is_nan());
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn mul_add(self, a: f32, b: f32) -> f32
[src]
Fused multiply-add. Computes (self * a) + b
with only one rounding error, yielding a more accurate result than an unfused multiply-add.
Using mul_add
can be more performant than an unfused multiply-add if the target architecture has a dedicated fma
CPU instruction.
let m = 10.0_f32; let x = 4.0_f32; let b = 60.0_f32; // 100.0 let abs_difference = (m.mul_add(x, b) - ((m * x) + b)).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn div_euclid(self, rhs: f32) -> f32
[src]1.38.0
Calculates Euclidean division, the matching method for rem_euclid
.
This computes the integer n
such that self = n * rhs + self.rem_euclid(rhs)
. In other words, the result is self / rhs
rounded to the integer n
such that self >= n * rhs
.
let a: f32 = 7.0; let b = 4.0; assert_eq!(a.div_euclid(b), 1.0); // 7.0 > 4.0 * 1.0 assert_eq!((-a).div_euclid(b), -2.0); // -7.0 >= 4.0 * -2.0 assert_eq!(a.div_euclid(-b), -1.0); // 7.0 >= -4.0 * -1.0 assert_eq!((-a).div_euclid(-b), 2.0); // -7.0 >= -4.0 * 2.0
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn rem_euclid(self, rhs: f32) -> f32
[src]1.38.0
Calculates the least nonnegative remainder of self (mod rhs)
.
In particular, the return value r
satisfies 0.0 <= r < rhs.abs()
in most cases. However, due to a floating point round-off error it can result in r == rhs.abs()
, violating the mathematical definition, if self
is much smaller than rhs.abs()
in magnitude and self < 0.0
. This result is not an element of the function's codomain, but it is the closest floating point number in the real numbers and thus fulfills the property self == self.div_euclid(rhs) * rhs + self.rem_euclid(rhs)
approximatively.
let a: f32 = 7.0; let b = 4.0; assert_eq!(a.rem_euclid(b), 3.0); assert_eq!((-a).rem_euclid(b), 1.0); assert_eq!(a.rem_euclid(-b), 3.0); assert_eq!((-a).rem_euclid(-b), 1.0); // limitation due to round-off error assert!((-f32::EPSILON).rem_euclid(3.0) != 0.0);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn powi(self, n: i32) -> f32
[src]
Raises a number to an integer power.
Using this function is generally faster than using powf
let x = 2.0_f32; let abs_difference = (x.powi(2) - (x * x)).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn powf(self, n: f32) -> f32
[src]
Raises a number to a floating point power.
let x = 2.0_f32; let abs_difference = (x.powf(2.0) - (x * x)).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn sqrt(self) -> f32
[src]
Returns the square root of a number.
Returns NaN if self
is a negative number.
let positive = 4.0_f32; let negative = -4.0_f32; let abs_difference = (positive.sqrt() - 2.0).abs(); assert!(abs_difference <= f32::EPSILON); assert!(negative.sqrt().is_nan());
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn exp(self) -> f32
[src]
Returns e^(self)
, (the exponential function).
let one = 1.0f32; // e^1 let e = one.exp(); // ln(e) - 1 == 0 let abs_difference = (e.ln() - 1.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn exp2(self) -> f32
[src]
Returns 2^(self)
.
let f = 2.0f32; // 2^2 - 4 == 0 let abs_difference = (f.exp2() - 4.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn ln(self) -> f32
[src]
Returns the natural logarithm of the number.
let one = 1.0f32; // e^1 let e = one.exp(); // ln(e) - 1 == 0 let abs_difference = (e.ln() - 1.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn log(self, base: f32) -> f32
[src]
Returns the logarithm of the number with respect to an arbitrary base.
The result may not be correctly rounded owing to implementation details; self.log2()
can produce more accurate results for base 2, and self.log10()
can produce more accurate results for base 10.
let five = 5.0f32; // log5(5) - 1 == 0 let abs_difference = (five.log(5.0) - 1.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn log2(self) -> f32
[src]
Returns the base 2 logarithm of the number.
let two = 2.0f32; // log2(2) - 1 == 0 let abs_difference = (two.log2() - 1.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn log10(self) -> f32
[src]
Returns the base 10 logarithm of the number.
let ten = 10.0f32; // log10(10) - 1 == 0 let abs_difference = (ten.log10() - 1.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn abs_sub(self, other: f32) -> f32
[src]
The positive difference of two numbers.
self <= other
: 0:0
self - other
let x = 3.0f32; let y = -3.0f32; let abs_difference_x = (x.abs_sub(1.0) - 2.0).abs(); let abs_difference_y = (y.abs_sub(1.0) - 0.0).abs(); assert!(abs_difference_x <= f32::EPSILON); assert!(abs_difference_y <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn cbrt(self) -> f32
[src]
Returns the cubic root of a number.
let x = 8.0f32; // x^(1/3) - 2 == 0 let abs_difference = (x.cbrt() - 2.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn hypot(self, other: f32) -> f32
[src]
Calculates the length of the hypotenuse of a right-angle triangle given legs of length x
and y
.
let x = 2.0f32; let y = 3.0f32; // sqrt(x^2 + y^2) let abs_difference = (x.hypot(y) - (x.powi(2) + y.powi(2)).sqrt()).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn sin(self) -> f32
[src]
Computes the sine of a number (in radians).
let x = std::f32::consts::FRAC_PI_2; let abs_difference = (x.sin() - 1.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn cos(self) -> f32
[src]
Computes the cosine of a number (in radians).
let x = 2.0 * std::f32::consts::PI; let abs_difference = (x.cos() - 1.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn tan(self) -> f32
[src]
Computes the tangent of a number (in radians).
let x = std::f32::consts::FRAC_PI_4; let abs_difference = (x.tan() - 1.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn asin(self) -> f32
[src]
Computes the arcsine of a number. Return value is in radians in the range [-pi/2, pi/2] or NaN if the number is outside the range [-1, 1].
let f = std::f32::consts::FRAC_PI_2; // asin(sin(pi/2)) let abs_difference = (f.sin().asin() - std::f32::consts::FRAC_PI_2).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn acos(self) -> f32
[src]
Computes the arccosine of a number. Return value is in radians in the range [0, pi] or NaN if the number is outside the range [-1, 1].
let f = std::f32::consts::FRAC_PI_4; // acos(cos(pi/4)) let abs_difference = (f.cos().acos() - std::f32::consts::FRAC_PI_4).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn atan(self) -> f32
[src]
Computes the arctangent of a number. Return value is in radians in the range [-pi/2, pi/2];
let f = 1.0f32; // atan(tan(1)) let abs_difference = (f.tan().atan() - 1.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn atan2(self, other: f32) -> f32
[src]
Computes the four quadrant arctangent of self
(y
) and other
(x
) in radians.
x = 0
, y = 0
: 0
x >= 0
: arctan(y/x)
-> [-pi/2, pi/2]
y >= 0
: arctan(y/x) + pi
-> (pi/2, pi]
y < 0
: arctan(y/x) - pi
-> (-pi, -pi/2)
// Positive angles measured counter-clockwise // from positive x axis // -pi/4 radians (45 deg clockwise) let x1 = 3.0f32; let y1 = -3.0f32; // 3pi/4 radians (135 deg counter-clockwise) let x2 = -3.0f32; let y2 = 3.0f32; let abs_difference_1 = (y1.atan2(x1) - (-std::f32::consts::FRAC_PI_4)).abs(); let abs_difference_2 = (y2.atan2(x2) - (3.0 * std::f32::consts::FRAC_PI_4)).abs(); assert!(abs_difference_1 <= f32::EPSILON); assert!(abs_difference_2 <= f32::EPSILON);
pub fn sin_cos(self) -> (f32, f32)
[src]
Simultaneously computes the sine and cosine of the number, x
. Returns (sin(x), cos(x))
.
let x = std::f32::consts::FRAC_PI_4; let f = x.sin_cos(); let abs_difference_0 = (f.0 - x.sin()).abs(); let abs_difference_1 = (f.1 - x.cos()).abs(); assert!(abs_difference_0 <= f32::EPSILON); assert!(abs_difference_1 <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn exp_m1(self) -> f32
[src]
Returns e^(self) - 1
in a way that is accurate even if the number is close to zero.
let x = 6.0f32; // e^(ln(6)) - 1 let abs_difference = (x.ln().exp_m1() - 5.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn ln_1p(self) -> f32
[src]
Returns ln(1+n)
(natural logarithm) more accurately than if the operations were performed separately.
let x = std::f32::consts::E - 1.0; // ln(1 + (e - 1)) == ln(e) == 1 let abs_difference = (x.ln_1p() - 1.0).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn sinh(self) -> f32
[src]
Hyperbolic sine function.
let e = std::f32::consts::E; let x = 1.0f32; let f = x.sinh(); // Solving sinh() at 1 gives `(e^2-1)/(2e)` let g = ((e * e) - 1.0) / (2.0 * e); let abs_difference = (f - g).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn cosh(self) -> f32
[src]
Hyperbolic cosine function.
let e = std::f32::consts::E; let x = 1.0f32; let f = x.cosh(); // Solving cosh() at 1 gives this result let g = ((e * e) + 1.0) / (2.0 * e); let abs_difference = (f - g).abs(); // Same result assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn tanh(self) -> f32
[src]
Hyperbolic tangent function.
let e = std::f32::consts::E; let x = 1.0f32; let f = x.tanh(); // Solving tanh() at 1 gives `(1 - e^(-2))/(1 + e^(-2))` let g = (1.0 - e.powi(-2)) / (1.0 + e.powi(-2)); let abs_difference = (f - g).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn asinh(self) -> f32
[src]
Inverse hyperbolic sine function.
let x = 1.0f32; let f = x.sinh().asinh(); let abs_difference = (f - x).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn acosh(self) -> f32
[src]
Inverse hyperbolic cosine function.
let x = 1.0f32; let f = x.cosh().acosh(); let abs_difference = (f - x).abs(); assert!(abs_difference <= f32::EPSILON);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn atanh(self) -> f32
[src]
Inverse hyperbolic tangent function.
let e = std::f32::consts::E; let f = e.tanh().atanh(); let abs_difference = (f - e).abs(); assert!(abs_difference <= 1e-5);
#[must_use =
"method returns a new number and does not mutate the original value"]pub fn clamp(self, min: f32, max: f32) -> f32
[src]
Restrict a value to a certain interval unless it is NaN.
Returns max
if self
is greater than max
, and min
if self
is less than min
. Otherwise this returns self
.
Note that this function returns NaN if the initial value was NaN as well.
Panics if min > max
, min
is NaN, or max
is NaN.
#![feature(clamp)] assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0); assert!((0.0f32).clamp(-2.0, 1.0) == 0.0); assert!((2.0f32).clamp(-2.0, 1.0) == 1.0); assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
impl f32
[src]
pub const RADIX: u32
[src]1.43.0
The radix or base of the internal representation of f32
.
pub const MANTISSA_DIGITS: u32
[src]1.43.0
Number of significant digits in base 2.
pub const DIGITS: u32
[src]1.43.0
Approximate number of significant digits in base 10.
pub const EPSILON: f32
[src]1.43.0
Machine epsilon value for f32
.
This is the difference between 1.0
and the next larger representable number.
pub const MIN: f32
[src]1.43.0
Smallest finite f32
value.
pub const MIN_POSITIVE: f32
[src]1.43.0
Smallest positive normal f32
value.
pub const MAX: f32
[src]1.43.0
Largest finite f32
value.
pub const MIN_EXP: i32
[src]1.43.0
One greater than the minimum possible normal power of 2 exponent.
pub const MAX_EXP: i32
[src]1.43.0
Maximum possible power of 2 exponent.
pub const MIN_10_EXP: i32
[src]1.43.0
Minimum possible normal power of 10 exponent.
pub const MAX_10_EXP: i32
[src]1.43.0
Maximum possible power of 10 exponent.
pub const NAN: f32
[src]1.43.0
Not a Number (NaN).
pub const INFINITY: f32
[src]1.43.0
Infinity (∞).
pub const NEG_INFINITY: f32
[src]1.43.0
Negative infinity (−∞).
pub fn is_nan(self) -> bool
[src]
Returns true
if this value is NaN
.
let nan = f32::NAN; let f = 7.0_f32; assert!(nan.is_nan()); assert!(!f.is_nan());
pub fn is_infinite(self) -> bool
[src]
Returns true
if this value is positive infinity or negative infinity, and false
otherwise.
let f = 7.0f32; let inf = f32::INFINITY; let neg_inf = f32::NEG_INFINITY; let nan = f32::NAN; assert!(!f.is_infinite()); assert!(!nan.is_infinite()); assert!(inf.is_infinite()); assert!(neg_inf.is_infinite());
pub fn is_finite(self) -> bool
[src]
Returns true
if this number is neither infinite nor NaN
.
let f = 7.0f32; let inf = f32::INFINITY; let neg_inf = f32::NEG_INFINITY; let nan = f32::NAN; assert!(f.is_finite()); assert!(!nan.is_finite()); assert!(!inf.is_finite()); assert!(!neg_inf.is_finite());
pub fn is_normal(self) -> bool
[src]
Returns true
if the number is neither zero, infinite, subnormal, or NaN
.
let min = f32::MIN_POSITIVE; // 1.17549435e-38f32 let max = f32::MAX; let lower_than_min = 1.0e-40_f32; let zero = 0.0_f32; assert!(min.is_normal()); assert!(max.is_normal()); assert!(!zero.is_normal()); assert!(!f32::NAN.is_normal()); assert!(!f32::INFINITY.is_normal()); // Values between `0` and `min` are Subnormal. assert!(!lower_than_min.is_normal());
pub fn classify(self) -> FpCategory
[src]
Returns the floating point category of the number. If only one property is going to be tested, it is generally faster to use the specific predicate instead.
use std::num::FpCategory; let num = 12.4_f32; let inf = f32::INFINITY; assert_eq!(num.classify(), FpCategory::Normal); assert_eq!(inf.classify(), FpCategory::Infinite);
pub fn is_sign_positive(self) -> bool
[src]
Returns true
if self
has a positive sign, including +0.0
, NaN
s with positive sign bit and positive infinity.
let f = 7.0_f32; let g = -7.0_f32; assert!(f.is_sign_positive()); assert!(!g.is_sign_positive());
pub fn is_sign_negative(self) -> bool
[src]
Returns true
if self
has a negative sign, including -0.0
, NaN
s with negative sign bit and negative infinity.
let f = 7.0f32; let g = -7.0f32; assert!(!f.is_sign_negative()); assert!(g.is_sign_negative());
pub fn recip(self) -> f32
[src]
Takes the reciprocal (inverse) of a number, 1/x
.
let x = 2.0_f32; let abs_difference = (x.recip() - (1.0 / x)).abs(); assert!(abs_difference <= f32::EPSILON);
pub fn to_degrees(self) -> f32
[src]1.7.0
Converts radians to degrees.
let angle = std::f32::consts::PI; let abs_difference = (angle.to_degrees() - 180.0).abs(); assert!(abs_difference <= f32::EPSILON);
pub fn to_radians(self) -> f32
[src]1.7.0
Converts degrees to radians.
let angle = 180.0f32; let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs(); assert!(abs_difference <= f32::EPSILON);
pub fn max(self, other: f32) -> f32
[src]
Returns the maximum of the two numbers.
let x = 1.0f32; let y = 2.0f32; assert_eq!(x.max(y), y);
If one of the arguments is NaN, then the other argument is returned.
pub fn min(self, other: f32) -> f32
[src]
Returns the minimum of the two numbers.
let x = 1.0f32; let y = 2.0f32; assert_eq!(x.min(y), x);
If one of the arguments is NaN, then the other argument is returned.
pub unsafe fn to_int_unchecked<Int>(self) -> Int where
f32: FloatToInt<Int>,
[src]1.44.0
Rounds toward zero and converts to any primitive integer type, assuming that the value is finite and fits in that type.
let value = 4.6_f32; let rounded = unsafe { value.to_int_unchecked::<u16>() }; assert_eq!(rounded, 4); let value = -128.9_f32; let rounded = unsafe { value.to_int_unchecked::<i8>() }; assert_eq!(rounded, i8::MIN);
The value must:
NaN
Int
, after truncating off its fractional partpub fn to_bits(self) -> u32
[src]1.20.0
Raw transmutation to u32
.
This is currently identical to transmute::<f32, u32>(self)
on all platforms.
See from_bits
for some discussion of the portability of this operation (there are almost no issues).
Note that this function is distinct from as
casting, which attempts to preserve the numeric value, and not the bitwise value.
assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting! assert_eq!((12.5f32).to_bits(), 0x41480000);
pub fn from_bits(v: u32) -> f32
[src]1.20.0
Raw transmutation from u32
.
This is currently identical to transmute::<u32, f32>(v)
on all platforms. It turns out this is incredibly portable, for two reasons:
However there is one caveat: prior to the 2008 version of IEEE-754, how to interpret the NaN signaling bit wasn't actually specified. Most platforms (notably x86 and ARM) picked the interpretation that was ultimately standardized in 2008, but some didn't (notably MIPS). As a result, all signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
Rather than trying to preserve signaling-ness cross-platform, this implementation favors preserving the exact bits. This means that any payloads encoded in NaNs will be preserved even if the result of this method is sent over the network from an x86 machine to a MIPS one.
If the results of this method are only manipulated by the same architecture that produced them, then there is no portability concern.
If the input isn't NaN, then there is no portability concern.
If you don't care about signalingness (very likely), then there is no portability concern.
Note that this function is distinct from as
casting, which attempts to preserve the numeric value, and not the bitwise value.
let v = f32::from_bits(0x41480000); assert_eq!(v, 12.5);
pub fn to_be_bytes(self) -> [u8; 4]
[src]1.40.0
Return the memory representation of this floating point number as a byte array in big-endian (network) byte order.
let bytes = 12.5f32.to_be_bytes(); assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
pub fn to_le_bytes(self) -> [u8; 4]
[src]1.40.0
Return the memory representation of this floating point number as a byte array in little-endian byte order.
let bytes = 12.5f32.to_le_bytes(); assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
pub fn to_ne_bytes(self) -> [u8; 4]
[src]1.40.0
Return the memory representation of this floating point number as a byte array in native byte order.
As the target platform's native endianness is used, portable code should use to_be_bytes
or to_le_bytes
, as appropriate, instead.
let bytes = 12.5f32.to_ne_bytes(); assert_eq!( bytes, if cfg!(target_endian = "big") { [0x41, 0x48, 0x00, 0x00] } else { [0x00, 0x00, 0x48, 0x41] } );
pub fn from_be_bytes(bytes: [u8; 4]) -> f32
[src]1.40.0
Create a floating point value from its representation as a byte array in big endian.
let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]); assert_eq!(value, 12.5);
pub fn from_le_bytes(bytes: [u8; 4]) -> f32
[src]1.40.0
Create a floating point value from its representation as a byte array in little endian.
let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]); assert_eq!(value, 12.5);
pub fn from_ne_bytes(bytes: [u8; 4]) -> f32
[src]1.40.0
Create a floating point value from its representation as a byte array in native endian.
As the target platform's native endianness is used, portable code likely wants to use from_be_bytes
or from_le_bytes
, as appropriate instead.
let value = f32::from_ne_bytes(if cfg!(target_endian = "big") { [0x41, 0x48, 0x00, 0x00] } else { [0x00, 0x00, 0x48, 0x41] }); assert_eq!(value, 12.5);
pub fn total_cmp(&self, other: &f32) -> Ordering
[src]
Returns an ordering between self and other values. Unlike the standard partial comparison between floating point numbers, this comparison always produces an ordering in accordance to the totalOrder predicate as defined in IEEE 754 (2008 revision) floating point standard. The values are ordered in following order:
#![feature(total_cmp)] struct GoodBoy { name: String, weight: f32, } let mut bois = vec![ GoodBoy { name: "Pucci".to_owned(), weight: 0.1 }, GoodBoy { name: "Woofer".to_owned(), weight: 99.0 }, GoodBoy { name: "Yapper".to_owned(), weight: 10.0 }, GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY }, GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN }, GoodBoy { name: "Floaty".to_owned(), weight: -5.0 }, ]; bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
impl<'_, '_> Add<&'_ f32> for &'_ f32
[src]
type Output = <f32 as Add<f32>>::Output
The resulting type after applying the +
operator.
fn add(self, other: &f32) -> <f32 as Add<f32>>::Output
[src]
impl<'_> Add<&'_ f32> for f32
[src]
type Output = <f32 as Add<f32>>::Output
The resulting type after applying the +
operator.
fn add(self, other: &f32) -> <f32 as Add<f32>>::Output
[src]
impl Add<f32> for f32
[src]
type Output = f32
The resulting type after applying the +
operator.
fn add(self, other: f32) -> f32
[src]
impl<'a> Add<f32> for &'a f32
[src]
type Output = <f32 as Add<f32>>::Output
The resulting type after applying the +
operator.
fn add(self, other: f32) -> <f32 as Add<f32>>::Output
[src]
impl<'_> AddAssign<&'_ f32> for f32
[src]1.22.0
fn add_assign(&mut self, other: &f32)
[src]
impl AddAssign<f32> for f32
[src]1.8.0
fn add_assign(&mut self, other: f32)
[src]
impl Clone for f32
[src]
impl Copy for f32
[src]
impl Debug for f32
[src]
impl Default for f32
[src]
impl Display for f32
[src]
impl<'_> Div<&'_ f32> for f32
[src]
type Output = <f32 as Div<f32>>::Output
The resulting type after applying the /
operator.
fn div(self, other: &f32) -> <f32 as Div<f32>>::Output
[src]
impl<'_, '_> Div<&'_ f32> for &'_ f32
[src]
type Output = <f32 as Div<f32>>::Output
The resulting type after applying the /
operator.
fn div(self, other: &f32) -> <f32 as Div<f32>>::Output
[src]
impl<'a> Div<f32> for &'a f32
[src]
type Output = <f32 as Div<f32>>::Output
The resulting type after applying the /
operator.
fn div(self, other: f32) -> <f32 as Div<f32>>::Output
[src]
impl Div<f32> for f32
[src]
type Output = f32
The resulting type after applying the /
operator.
fn div(self, other: f32) -> f32
[src]
impl<'_> DivAssign<&'_ f32> for f32
[src]1.22.0
fn div_assign(&mut self, other: &f32)
[src]
impl DivAssign<f32> for f32
[src]1.8.0
fn div_assign(&mut self, other: f32)
[src]
impl FloatToInt<i128> for f32
[src]
impl FloatToInt<i16> for f32
[src]
impl FloatToInt<i32> for f32
[src]
impl FloatToInt<i64> for f32
[src]
impl FloatToInt<i8> for f32
[src]
impl FloatToInt<isize> for f32
[src]
impl FloatToInt<u128> for f32
[src]
impl FloatToInt<u16> for f32
[src]
impl FloatToInt<u32> for f32
[src]
impl FloatToInt<u64> for f32
[src]
impl FloatToInt<u8> for f32
[src]
impl FloatToInt<usize> for f32
[src]
impl From<i16> for f32
[src]1.6.0
Converts i16
to f32
losslessly.
impl From<i8> for f32
[src]1.6.0
Converts i8
to f32
losslessly.
impl From<u16> for f32
[src]1.6.0
Converts u16
to f32
losslessly.
impl From<u8> for f32
[src]1.6.0
Converts u8
to f32
losslessly.
impl FromStr for f32
[src]
type Err = ParseFloatError
The associated error which can be returned from parsing.
fn from_str(src: &str) -> Result<f32, ParseFloatError>
[src]
Converts a string in base 10 to a float. Accepts an optional decimal exponent.
This function accepts strings such as
Leading and trailing whitespace represent an error.
All strings that adhere to the following EBNF grammar will result in an Ok
being returned:
Float ::= Sign? ( 'inf' | 'NaN' | Number ) Number ::= ( Digit+ | Digit+ '.' Digit* | Digit* '.' Digit+ ) Exp? Exp ::= [eE] Sign? Digit+ Sign ::= [+-] Digit ::= [0-9]
In some situations, some strings that should create a valid float instead return an error. See issue #31407 for details.
Err(ParseFloatError)
if the string did not represent a valid number. Otherwise, Ok(n)
where n
is the floating-point number represented by src
.
impl LowerExp for f32
[src]
impl<'_, '_> Mul<&'_ f32> for &'_ f32
[src]
type Output = <f32 as Mul<f32>>::Output
The resulting type after applying the *
operator.
fn mul(self, other: &f32) -> <f32 as Mul<f32>>::Output
[src]
impl<'_> Mul<&'_ f32> for f32
[src]
type Output = <f32 as Mul<f32>>::Output
The resulting type after applying the *
operator.
fn mul(self, other: &f32) -> <f32 as Mul<f32>>::Output
[src]
impl Mul<f32> for f32
[src]
type Output = f32
The resulting type after applying the *
operator.
fn mul(self, other: f32) -> f32
[src]
impl<'a> Mul<f32> for &'a f32
[src]
type Output = <f32 as Mul<f32>>::Output
The resulting type after applying the *
operator.
fn mul(self, other: f32) -> <f32 as Mul<f32>>::Output
[src]
impl<'_> MulAssign<&'_ f32> for f32
[src]1.22.0
fn mul_assign(&mut self, other: &f32)
[src]
impl MulAssign<f32> for f32
[src]1.8.0
fn mul_assign(&mut self, other: f32)
[src]
impl<'_> Neg for &'_ f32
[src]
type Output = <f32 as Neg>::Output
The resulting type after applying the -
operator.
fn neg(self) -> <f32 as Neg>::Output
[src]
impl Neg for f32
[src]
impl PartialEq<f32> for f32
[src]
impl PartialOrd<f32> for f32
[src]
fn partial_cmp(&self, other: &f32) -> Option<Ordering>
[src]
fn lt(&self, other: &f32) -> bool
[src]
fn le(&self, other: &f32) -> bool
[src]
fn ge(&self, other: &f32) -> bool
[src]
fn gt(&self, other: &f32) -> bool
[src]
impl<'a> Product<&'a f32> for f32
[src]1.12.0
impl Product<f32> for f32
[src]1.12.0
impl<'_> Rem<&'_ f32> for f32
[src]
type Output = <f32 as Rem<f32>>::Output
The resulting type after applying the %
operator.
fn rem(self, other: &f32) -> <f32 as Rem<f32>>::Output
[src]
impl<'_, '_> Rem<&'_ f32> for &'_ f32
[src]
type Output = <f32 as Rem<f32>>::Output
The resulting type after applying the %
operator.
fn rem(self, other: &f32) -> <f32 as Rem<f32>>::Output
[src]
impl Rem<f32> for f32
[src]
The remainder from the division of two floats.
The remainder has the same sign as the dividend and is computed as: x - (x / y).trunc() * y
.
let x: f32 = 50.50; let y: f32 = 8.125; let remainder = x - (x / y).trunc() * y; // The answer to both operations is 1.75 assert_eq!(x % y, remainder);
type Output = f32
The resulting type after applying the %
operator.
fn rem(self, other: f32) -> f32
[src]
impl<'a> Rem<f32> for &'a f32
[src]
type Output = <f32 as Rem<f32>>::Output
The resulting type after applying the %
operator.
fn rem(self, other: f32) -> <f32 as Rem<f32>>::Output
[src]
impl<'_> RemAssign<&'_ f32> for f32
[src]1.22.0
fn rem_assign(&mut self, other: &f32)
[src]
impl RemAssign<f32> for f32
[src]1.8.0
fn rem_assign(&mut self, other: f32)
[src]
impl<'_> Sub<&'_ f32> for f32
[src]
type Output = <f32 as Sub<f32>>::Output
The resulting type after applying the -
operator.
fn sub(self, other: &f32) -> <f32 as Sub<f32>>::Output
[src]
impl<'_, '_> Sub<&'_ f32> for &'_ f32
[src]
type Output = <f32 as Sub<f32>>::Output
The resulting type after applying the -
operator.
fn sub(self, other: &f32) -> <f32 as Sub<f32>>::Output
[src]
impl<'a> Sub<f32> for &'a f32
[src]
type Output = <f32 as Sub<f32>>::Output
The resulting type after applying the -
operator.
fn sub(self, other: f32) -> <f32 as Sub<f32>>::Output
[src]
impl Sub<f32> for f32
[src]
type Output = f32
The resulting type after applying the -
operator.
fn sub(self, other: f32) -> f32
[src]
impl<'_> SubAssign<&'_ f32> for f32
[src]1.22.0
fn sub_assign(&mut self, other: &f32)
[src]
impl SubAssign<f32> for f32
[src]1.8.0
fn sub_assign(&mut self, other: f32)
[src]
impl<'a> Sum<&'a f32> for f32
[src]1.12.0
impl Sum<f32> for f32
[src]1.12.0
impl UpperExp for f32
[src]
impl RefUnwindSafe for f32
impl Send for f32
impl Sync for f32
impl Unpin for f32
impl UnwindSafe for f32
impl<T> Any for T where
T: 'static + ?Sized,
[src]
impl<T> Borrow<T> for T where
T: ?Sized,
[src]
fn borrow(&self) -> &TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> BorrowMut<T> for T where
T: ?Sized,
[src]
fn borrow_mut(&mut self) -> &mut TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> From<T> for T
[src]
impl<T, U> Into<U> for T where
U: From<T>,
[src]
impl<T> ToOwned for T where
T: Clone,
[src]
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
[src]
fn clone_into(&self, target: &mut T)
[src]
impl<T> ToString for T where
T: Display + ?Sized,
[src]
impl<T, U> TryFrom<U> for T where
U: Into<T>,
[src]
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
[src]
impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
[src]
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/primitive.f32.html