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 = 2u32

The radix or base of the internal representation of f64.

pub const MANTISSA_DIGITS: u32 = 53u32

Number of significant digits in base 2.

Note that the size of the mantissa in the bitwise representation is one smaller than this since the leading 1 is not stored explicitly.

pub const DIGITS: u32 = 15u32

Approximate number of significant digits in base 10.

This is the maximum x such that any decimal number with x significant digits can be converted to f64 and back without loss.

Equal to floor(log₁₀ 2^{MANTISSA_DIGITS − 1}).

pub const EPSILON: f64 = 2.2204460492503131E-16f64

Machine epsilon value for f64.

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

Equal to 2^{1 − MANTISSA_DIGITS}.

pub const MIN: f64 = -1.7976931348623157E+308f64

Smallest finite f64 value.

Equal to −MAX.

pub const MIN_POSITIVE: f64 = 2.2250738585072014E-308f64

Smallest positive normal f64 value.

Equal to 2^{MIN_EXP − 1}.

pub const MAX: f64 = 1.7976931348623157E+308f64

Largest finite f64 value.

Equal to (1 − 2^{−MANTISSA_DIGITS}) 2^MAX_EXP.

pub const MIN_EXP: i32 = -1_021i32

One greater than the minimum possible normal power of 2 exponent for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).

This corresponds to the exact minimum possible normal power of 2 exponent for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition). In other words, all normal numbers representable by this type are greater than or equal to 0.5 × 2^MIN_EXP.

pub const MAX_EXP: i32 = 1_024i32

One greater than the maximum possible power of 2 exponent for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).

This corresponds to the exact maximum possible power of 2 exponent for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition). In other words, all numbers representable by this type are strictly less than 2^MAX_EXP.

pub const MIN_10_EXP: i32 = -307i32

Minimum x for which 10^x is normal.

Equal to ceil(log₁₀ MIN_POSITIVE).

pub const MAX_10_EXP: i32 = 308i32

Maximum x for which 10^x is normal.

Equal to floor(log₁₀ MAX).

pub const NAN: f64 = NaN_f64

Not a Number (NaN).

Note that IEEE 754 doesn’t define just a single NaN value; a plethora of bit patterns are considered to be NaN. Furthermore, the standard makes a difference between a “signaling” and a “quiet” NaN, and allows inspecting its “payload” (the unspecified bits in the bit pattern) and its sign. See the specification of NaN bit patterns for more info.

This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary. The concrete bit pattern may change across Rust versions and target platforms.

pub const INFINITY: f64 = +Inf_f64

Infinity (∞).

pub const NEG_INFINITY: f64 = -Inf_f64

Negative infinity (−∞).

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

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

See from_bits for some discussion of the portability of this operation (there are almost no issues).

Examples

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

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

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

See from_bits for some discussion of the portability of this operation (there are almost no issues).

Examples

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

Trait Implementations

impl Add<&f64> for &f64

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

The resulting type after applying the + operator.

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

Performs the + operation.

impl Add for f64

type Output = f64

The resulting type after applying the + operator.

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

Performs the + operation.

impl AddAssign<&f64> for f64

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

Performs the += operation.

impl AddAssign for f64

fn add_assign(&mut self, other: f64)

Performs the += operation.

impl Clone for f64

fn clone(&self) -> Self

Returns a duplicate of the value.

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

where Self:,

Performs copy-assignment from source.

impl Default for f64

fn default() -> f64

Returns the default value of 0.0

impl Div<&f64> for &f64

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

The resulting type after applying the / operator.

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

Performs the / operation.

impl Div for f64

type Output = f64

The resulting type after applying the / operator.

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

Performs the / operation.

impl DivAssign<&f64> for f64

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

Performs the /= operation.

impl DivAssign for f64

fn div_assign(&mut self, other: f64)

Performs the /= operation.

impl Mul<&f64> for &f64

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

The resulting type after applying the * operator.

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

Performs the * operation.

impl Mul for f64

type Output = f64

The resulting type after applying the * operator.

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

Performs the * operation.

impl MulAssign<&f64> for f64

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

Performs the *= operation.

impl MulAssign for f64

fn mul_assign(&mut self, other: f64)

Performs the *= 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 Neg for f64

type Output = f64

The resulting type after applying the - operator.

fn neg(self) -> f64

Performs the unary - operation.

impl PartialEq for f64

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for f64

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

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

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

Tests less than (for self and other) and is used by the < operator.

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

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

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

Tests greater than (for self and other) and is used by the > operator.

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

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

impl Rem<&f64> for &f64

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

The resulting type after applying the % operator.

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

Performs the % operation.

impl Rem 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 RemAssign<&f64> for f64

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

Performs the %= operation.

impl RemAssign for f64

fn rem_assign(&mut self, other: f64)

Performs the %= operation.

impl Sub<&f64> for &f64

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

The resulting type after applying the - operator.

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

Performs the - operation.

impl Sub for f64

type Output = f64

The resulting type after applying the - operator.

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

Performs the - operation.

impl SubAssign<&f64> for f64

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

Performs the -= operation.

impl SubAssign for f64

fn sub_assign(&mut self, other: f64)

Performs the -= operation.

impl Copy for f64