Primitive Type f64

A 64-bit floating point type (specifically, the “binary64” type defined in IEEE 754-2008).

This type is very similar to f32, but has increased precision by using twice as many bits. Please see the documentation for f32 or Wikipedia on double precision values for more information.

See also the std::f64::consts module.

Implementations

impl f64

pub const RADIX: u32

The radix or base of the internal representation of f64.

pub const MANTISSA_DIGITS: u32

Number of significant digits in base 2.

pub const DIGITS: u32

Approximate number of significant digits in base 10.

pub const EPSILON: f64

Machine epsilon value for f64.

This is the difference between 1.0 and the next larger representable number.

pub const MIN: f64

Smallest finite f64 value.

pub const MIN_POSITIVE: f64

Smallest positive normal f64 value.

pub const MAX: f64

Largest finite f64 value.

pub const MIN_EXP: i32

One greater than the minimum possible normal power of 2 exponent.

pub const MAX_EXP: i32

Maximum possible power of 2 exponent.

pub const MIN_10_EXP: i32

Minimum possible normal power of 10 exponent.

pub const MAX_10_EXP: i32

Maximum possible power of 10 exponent.

pub const NAN: f64

Not a Number (NaN).

pub const INFINITY: f64

Infinity (∞).

pub const NEG_INFINITY: f64

Negative infinity (−∞).

pub fn is_nan(self) -> bool

Returns true if this value is NaN.

let nan = f64::NAN;
let f = 7.0_f64;

assert!(nan.is_nan());
assert!(!f.is_nan());

pub fn is_infinite(self) -> bool

Returns true if this value is positive infinity or negative infinity, and false otherwise.

let f = 7.0f64;
let inf = f64::INFINITY;
let neg_inf = f64::NEG_INFINITY;
let nan = f64::NAN;

assert!(!f.is_infinite());
assert!(!nan.is_infinite());

assert!(inf.is_infinite());
assert!(neg_inf.is_infinite());

pub fn is_finite(self) -> bool

Returns true if this number is neither infinite nor NaN.

let f = 7.0f64;
let inf: f64 = f64::INFINITY;
let neg_inf: f64 = f64::NEG_INFINITY;
let nan: f64 = f64::NAN;

assert!(f.is_finite());

assert!(!nan.is_finite());
assert!(!inf.is_finite());
assert!(!neg_inf.is_finite());

pub fn is_subnormal(self) -> bool

Returns true if the number is subnormal.

let min = f64::MIN_POSITIVE; // 2.2250738585072014e-308_f64
let max = f64::MAX;
let lower_than_min = 1.0e-308_f64;
let zero = 0.0_f64;

assert!(!min.is_subnormal());
assert!(!max.is_subnormal());

assert!(!zero.is_subnormal());
assert!(!f64::NAN.is_subnormal());
assert!(!f64::INFINITY.is_subnormal());
// Values between `0` and `min` are Subnormal.
assert!(lower_than_min.is_subnormal());

pub fn is_normal(self) -> bool

Returns true if the number is neither zero, infinite, subnormal, or NaN.

let min = f64::MIN_POSITIVE; // 2.2250738585072014e-308f64
let max = f64::MAX;
let lower_than_min = 1.0e-308_f64;
let zero = 0.0f64;

assert!(min.is_normal());
assert!(max.is_normal());

assert!(!zero.is_normal());
assert!(!f64::NAN.is_normal());
assert!(!f64::INFINITY.is_normal());
// Values between `0` and `min` are Subnormal.
assert!(!lower_than_min.is_normal());

pub fn classify(self) -> FpCategory

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_f64;
let inf = f64::INFINITY;

assert_eq!(num.classify(), FpCategory::Normal);
assert_eq!(inf.classify(), FpCategory::Infinite);

pub fn is_sign_positive(self) -> bool

Returns true if self has a positive sign, including +0.0, NaNs with positive sign bit and positive infinity.

let f = 7.0_f64;
let g = -7.0_f64;

assert!(f.is_sign_positive());
assert!(!g.is_sign_positive());

pub fn is_sign_negative(self) -> bool

Returns true if self has a negative sign, including -0.0, NaNs with negative sign bit and negative infinity.

let f = 7.0_f64;
let g = -7.0_f64;

assert!(!f.is_sign_negative());
assert!(g.is_sign_negative());

pub fn recip(self) -> f64

Takes the reciprocal (inverse) of a number, 1/x.

let x = 2.0_f64;
let abs_difference = (x.recip() - (1.0 / x)).abs();

assert!(abs_difference < 1e-10);

pub fn to_degrees(self) -> f64

Converts radians to degrees.

let angle = std::f64::consts::PI;

let abs_difference = (angle.to_degrees() - 180.0).abs();

assert!(abs_difference < 1e-10);

pub fn to_radians(self) -> f64

Converts degrees to radians.

let angle = 180.0_f64;

let abs_difference = (angle.to_radians() - std::f64::consts::PI).abs();

assert!(abs_difference < 1e-10);

pub fn max(self, other: f64) -> f64

Returns the maximum of the two numbers.

Follows the IEEE-754 2008 semantics for maxNum, except for handling of signaling NaNs. This matches the behavior of libm’s fmax.

let x = 1.0_f64;
let y = 2.0_f64;

assert_eq!(x.max(y), y);

If one of the arguments is NaN, then the other argument is returned.

pub fn min(self, other: f64) -> f64

Returns the minimum of the two numbers.

Follows the IEEE-754 2008 semantics for minNum, except for handling of signaling NaNs. This matches the behavior of libm’s fmin.

let x = 1.0_f64;
let y = 2.0_f64;

assert_eq!(x.min(y), x);

If one of the arguments is NaN, then the other argument is returned.

pub fn maximum(self, other: f64) -> f64

🔬 This is a nightly-only experimental API. (float_minimum_maximum #91079)

Returns the maximum of the two numbers, propagating NaNs.

This returns NaN when either argument is NaN, as opposed to f64::max which only returns NaN when both arguments are NaN.

#![feature(float_minimum_maximum)]
let x = 1.0_f64;
let y = 2.0_f64;

assert_eq!(x.maximum(y), y);
assert!(x.maximum(f64::NAN).is_nan());

If one of the arguments is NaN, then NaN is returned. Otherwise this returns the greater of the two numbers. For this operation, -0.0 is considered to be less than +0.0. Note that this follows the semantics specified in IEEE 754-2019.

pub fn minimum(self, other: f64) -> f64

🔬 This is a nightly-only experimental API. (float_minimum_maximum #91079)

Returns the minimum of the two numbers, propagating NaNs.

This returns NaN when either argument is NaN, as opposed to f64::min which only returns NaN when both arguments are NaN.

#![feature(float_minimum_maximum)]
let x = 1.0_f64;
let y = 2.0_f64;

assert_eq!(x.minimum(y), x);
assert!(x.minimum(f64::NAN).is_nan());

If one of the arguments is NaN, then NaN is returned. Otherwise this returns the lesser of the two numbers. For this operation, -0.0 is considered to be less than +0.0. Note that this follows the semantics specified in IEEE 754-2019.

pub unsafe fn to_int_unchecked<Int>(self) -> Int where
    Self: FloatToInt<Int>, 

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_f64;
let rounded = unsafe { value.to_int_unchecked::<u16>() };
assert_eq!(rounded, 4);

let value = -128.9_f64;
let rounded = unsafe { value.to_int_unchecked::<i8>() };
assert_eq!(rounded, i8::MIN);

Safety

The value must:

• Not be NaN
• Not be infinite
• Be representable in the return type Int, after truncating off its fractional part

pub fn to_bits(self) -> u64

Raw transmutation to u64.

This is currently identical to transmute::<f64, u64>(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.

Examples

assert!((1f64).to_bits() != 1f64 as u64); // to_bits() is not casting!
assert_eq!((12.5f64).to_bits(), 0x4029000000000000);

pub fn from_bits(v: u64) -> Self

Raw transmutation from u64.

This is currently identical to transmute::<u64, f64>(v) on all platforms. It turns out this is incredibly portable, for two reasons:

• Floats and Ints have the same endianness on all supported platforms.
• IEEE-754 very precisely specifies the bit layout of floats.

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 signaling-ness (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.

Examples

let v = f64::from_bits(0x4029000000000000);
assert_eq!(v, 12.5);

pub fn to_be_bytes(self) -> [u8; 8]

Return the memory representation of this floating point number as a byte array in big-endian (network) byte order.

Examples

let bytes = 12.5f64.to_be_bytes();
assert_eq!(bytes, [0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);

pub fn to_le_bytes(self) -> [u8; 8]

Return the memory representation of this floating point number as a byte array in little-endian byte order.

Examples

let bytes = 12.5f64.to_le_bytes();
assert_eq!(bytes, [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x40]);

pub fn to_ne_bytes(self) -> [u8; 8]

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.

Examples

let bytes = 12.5f64.to_ne_bytes();
assert_eq!(
    bytes,
    if cfg!(target_endian = "big") {
        [0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
    } else {
        [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x40]
    }
);

pub fn from_be_bytes(bytes: [u8; 8]) -> Self

Create a floating point value from its representation as a byte array in big endian.

Examples

let value = f64::from_be_bytes([0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);
assert_eq!(value, 12.5);

pub fn from_le_bytes(bytes: [u8; 8]) -> Self

Create a floating point value from its representation as a byte array in little endian.

Examples

let value = f64::from_le_bytes([0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x40]);
assert_eq!(value, 12.5);

pub fn from_ne_bytes(bytes: [u8; 8]) -> Self

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.

Examples

let value = f64::from_ne_bytes(if cfg!(target_endian = "big") {
    [0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
} else {
    [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x40]
});
assert_eq!(value, 12.5);

pub fn total_cmp(&self, other: &Self) -> Ordering

🔬 This is a nightly-only experimental API. (total_cmp #72599)

Return the ordering between self and other.

Unlike the standard partial comparison between floating point numbers, this comparison always produces an ordering in accordance to the totalOrder predicate as defined in the IEEE 754 (2008 revision) floating point standard. The values are ordered in the following sequence:

• negative quiet NaN
• negative signaling NaN
• negative infinity
• negative numbers
• negative subnormal numbers
• negative zero
• positive zero
• positive subnormal numbers
• positive numbers
• positive infinity
• positive signaling NaN
• positive quiet NaN.

The ordering established by this function does not always agree with the PartialOrd and PartialEq implementations of f64. For example, they consider negative and positive zero equal, while total_cmp doesn’t.

The interpretation of the signaling NaN bit follows the definition in the IEEE 754 standard, which may not match the interpretation by some of the older, non-conformant (e.g. MIPS) hardware implementations.

Example

#![feature(total_cmp)]
struct GoodBoy {
    name: String,
    weight: f64,
}

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: f64::INFINITY },
    GoodBoy { name: "Abs. Unit".to_owned(), weight: f64::NAN },
    GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
];

bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));

pub fn clamp(self, min: f64, max: f64) -> f64

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

Panics if min > max, min is NaN, or max is NaN.

Examples

assert!((-3.0f64).clamp(-2.0, 1.0) == -2.0);
assert!((0.0f64).clamp(-2.0, 1.0) == 0.0);
assert!((2.0f64).clamp(-2.0, 1.0) == 1.0);
assert!((f64::NAN).clamp(-2.0, 1.0).is_nan());

Trait Implementations

impl Add<&'_ f64> for f64

type Output = <f64 as Add<f64>>::Output

The resulting type after applying the + operator.

fn add(self, other: &f64) -> <f64 as Add<f64>>::Output

Performs the + operation.

impl Add<&'_ f64> for &f64

type Output = <f64 as Add<f64>>::Output

The resulting type after applying the + operator.

fn add(self, other: &f64) -> <f64 as Add<f64>>::Output

Performs the + operation.

impl Add<f64> for f64

type Output = f64

The resulting type after applying the + operator.

fn add(self, other: f64) -> f64

Performs the + operation.

impl<'a> Add<f64> for &'a f64

type Output = <f64 as Add<f64>>::Output

The resulting type after applying the + operator.

fn add(self, other: f64) -> <f64 as Add<f64>>::Output

Performs the + operation.

impl AddAssign<&'_ f64> for f64

fn add_assign(&mut self, other: &f64)

Performs the += operation.

impl AddAssign<f64> for f64

fn add_assign(&mut self, other: f64)

Performs the += operation.

impl Clone for f64

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for f64

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for f64

fn default() -> f64

Returns the default value of 0.0

impl Display for f64

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Div<&'_ f64> for f64

type Output = <f64 as Div<f64>>::Output

The resulting type after applying the / operator.

fn div(self, other: &f64) -> <f64 as Div<f64>>::Output

Performs the / operation.

impl Div<&'_ f64> for &f64

type Output = <f64 as Div<f64>>::Output

The resulting type after applying the / operator.

fn div(self, other: &f64) -> <f64 as Div<f64>>::Output

Performs the / operation.

impl Div<f64> for f64

type Output = f64

The resulting type after applying the / operator.

fn div(self, other: f64) -> f64

Performs the / operation.

impl<'a> Div<f64> for &'a f64

type Output = <f64 as Div<f64>>::Output

The resulting type after applying the / operator.

fn div(self, other: f64) -> <f64 as Div<f64>>::Output

Performs the / operation.

impl DivAssign<&'_ f64> for f64

fn div_assign(&mut self, other: &f64)

Performs the /= operation.

impl DivAssign<f64> for f64

fn div_assign(&mut self, other: f64)

Performs the /= operation.

impl From<f32> for f64

fn from(small: f32) -> Self

Converts f32 to f64 losslessly.

impl From<i16> for f64

fn from(small: i16) -> Self

Converts i16 to f64 losslessly.

impl From<i32> for f64

fn from(small: i32) -> Self

Converts i32 to f64 losslessly.

impl From<i8> for f64

fn from(small: i8) -> Self

Converts i8 to f64 losslessly.

impl From<u16> for f64

fn from(small: u16) -> Self

Converts u16 to f64 losslessly.

impl From<u32> for f64

fn from(small: u32) -> Self

Converts u32 to f64 losslessly.

impl From<u8> for f64

fn from(small: u8) -> Self

Converts u8 to f64 losslessly.

impl FromStr for f64

fn from_str(src: &str) -> Result<Self, ParseFloatError>

Converts a string in base 10 to a float. Accepts an optional decimal exponent.

This function accepts strings such as

• ‘3.14’
• ‘-3.14’
• ‘2.5E10’, or equivalently, ‘2.5e10’
• ‘2.5E-10’
• ‘5.’
• ‘.5’, or, equivalently, ‘0.5’
• ‘inf’, ‘-inf’, ‘NaN’

Leading and trailing whitespace represent an error.

Grammar

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]

Arguments

• src - A string

Return value

Err(ParseFloatError) if the string did not represent a valid number. Otherwise, Ok(n) where n is the floating-point number represented by src.

type Err = ParseFloatError

The associated error which can be returned from parsing.

impl LowerExp for f64

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Mul<&'_ f64> for f64

type Output = <f64 as Mul<f64>>::Output

The resulting type after applying the * operator.

fn mul(self, other: &f64) -> <f64 as Mul<f64>>::Output

Performs the * operation.

impl Mul<&'_ f64> for &f64

type Output = <f64 as Mul<f64>>::Output

The resulting type after applying the * operator.

fn mul(self, other: &f64) -> <f64 as Mul<f64>>::Output

Performs the * operation.

impl Mul<f64> for f64

type Output = f64

The resulting type after applying the * operator.

fn mul(self, other: f64) -> f64

Performs the * operation.

impl<'a> Mul<f64> for &'a f64

type Output = <f64 as Mul<f64>>::Output

The resulting type after applying the * operator.

fn mul(self, other: f64) -> <f64 as Mul<f64>>::Output

Performs the * operation.

impl MulAssign<&'_ f64> for f64

fn mul_assign(&mut self, other: &f64)

Performs the *= operation.

impl MulAssign<f64> for f64

fn mul_assign(&mut self, other: f64)

Performs the *= operation.

impl Neg for f64

type Output = f64

The resulting type after applying the - operator.

fn neg(self) -> f64

Performs the unary - operation.

impl Neg for &f64

type Output = <f64 as Neg>::Output

The resulting type after applying the - operator.

fn neg(self) -> <f64 as Neg>::Output

Performs the unary - operation.

impl PartialEq<f64> for f64

fn eq(&self, other: &f64) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &f64) -> bool

This method tests for !=.

impl PartialOrd<f64> for f64

fn partial_cmp(&self, other: &f64) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &f64) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &f64) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn ge(&self, other: &f64) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

fn gt(&self, other: &f64) -> bool

This method tests greater than (for self and other) and is used by the > operator.

impl<'a> Product<&'a f64> for f64

fn product<I: Iterator<Item = &'a Self>>(iter: I) -> Self

Method which takes an iterator and generates Self from the elements by multiplying the items.

impl Product<f64> for f64

fn product<I: Iterator<Item = Self>>(iter: I) -> Self

Method which takes an iterator and generates Self from the elements by multiplying the items.

impl Rem<&'_ f64> for f64

type Output = <f64 as Rem<f64>>::Output

The resulting type after applying the % operator.

fn rem(self, other: &f64) -> <f64 as Rem<f64>>::Output

Performs the % operation.

impl Rem<&'_ f64> for &f64

type Output = <f64 as Rem<f64>>::Output

The resulting type after applying the % operator.

fn rem(self, other: &f64) -> <f64 as Rem<f64>>::Output

Performs the % operation.

impl Rem<f64> for f64

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.

Examples

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 = f64

The resulting type after applying the % operator.

fn rem(self, other: f64) -> f64

Performs the % operation.

impl<'a> Rem<f64> for &'a f64

type Output = <f64 as Rem<f64>>::Output

The resulting type after applying the % operator.

fn rem(self, other: f64) -> <f64 as Rem<f64>>::Output

Performs the % operation.

impl RemAssign<&'_ f64> for f64

fn rem_assign(&mut self, other: &f64)

Performs the %= operation.

impl RemAssign<f64> for f64

fn rem_assign(&mut self, other: f64)

Performs the %= operation.

impl SimdElement for f64

type Mask = i64

🔬 This is a nightly-only experimental API. (portable_simd #86656)

The mask element type corresponding to this element type.

impl Sub<&'_ f64> for f64

type Output = <f64 as Sub<f64>>::Output

The resulting type after applying the - operator.

fn sub(self, other: &f64) -> <f64 as Sub<f64>>::Output

Performs the - operation.

impl Sub<&'_ f64> for &f64

type Output = <f64 as Sub<f64>>::Output

The resulting type after applying the - operator.

fn sub(self, other: &f64) -> <f64 as Sub<f64>>::Output

Performs the - operation.

impl Sub<f64> for f64

type Output = f64

The resulting type after applying the - operator.

fn sub(self, other: f64) -> f64

Performs the - operation.

impl<'a> Sub<f64> for &'a f64

type Output = <f64 as Sub<f64>>::Output

The resulting type after applying the - operator.

fn sub(self, other: f64) -> <f64 as Sub<f64>>::Output

Performs the - operation.

impl SubAssign<&'_ f64> for f64

fn sub_assign(&mut self, other: &f64)

Performs the -= operation.

impl SubAssign<f64> for f64

fn sub_assign(&mut self, other: f64)

Performs the -= operation.

impl<'a> Sum<&'a f64> for f64

fn sum<I: Iterator<Item = &'a Self>>(iter: I) -> Self

Method which takes an iterator and generates Self from the elements by “summing up” the items.

impl Sum<f64> for f64

fn sum<I: Iterator<Item = Self>>(iter: I) -> Self

Method which takes an iterator and generates Self from the elements by “summing up” the items.

impl UpperExp for f64

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Copy for f64

impl FloatToInt<i128> for f64

impl FloatToInt<i16> for f64

impl FloatToInt<i32> for f64

impl FloatToInt<i64> for f64

impl FloatToInt<i8> for f64

impl FloatToInt<isize> for f64

impl FloatToInt<u128> for f64

impl FloatToInt<u16> for f64

impl FloatToInt<u32> for f64

impl FloatToInt<u64> for f64

impl FloatToInt<u8> for f64

impl FloatToInt<usize> for f64