# Constants
> Double-precision floating-point mathematical constants.
## Usage
```javascript
var constants = require( '@stdlib/constants/float64' );
```
#### constants
Double-precision floating-point mathematical constants.
```javascript
var c = constants;
// returns {...}
```
- [`APERY`][@stdlib/constants/float64/apery]: Apéry's constant.
- [`CATALAN`][@stdlib/constants/float64/catalan]: Catalan's constant.
- [`CBRT_EPS`][@stdlib/constants/float64/cbrt-eps]: cube root of double-precision floating-point epsilon.
- [`E`][@stdlib/constants/float64/e]: the mathematical constant _e_.
- [`EPS`][@stdlib/constants/float64/eps]: difference between one and the smallest value greater than one that can be represented as a double-precision floating-point number.
- [`EULERGAMMA`][@stdlib/constants/float64/eulergamma]: the Euler-Mascheroni constant.
- [`EXPONENT_BIAS`][@stdlib/constants/float64/exponent-bias]: the bias of a double-precision floating-point number's exponent.
- [`FOURTH_PI`][@stdlib/constants/float64/fourth-pi]: one fourth times the mathematical constant π.
- [`FOURTH_ROOT_EPS`][@stdlib/constants/float64/fourth-root-eps]: fourth root of double-precision floating-point epsilon.
- [`GAMMA_LANCZOS_G`][@stdlib/constants/float64/gamma-lanczos-g]: arbitrary constant `g` to be used in Lanczos approximation functions.
- [`GLAISHER`][@stdlib/constants/float64/glaisher-kinkelin]: Glaisher-Kinkelin constant.
- [`HALF_LN2`][@stdlib/constants/float64/half-ln-two]: one half times the natural logarithm of 2.
- [`HALF_PI`][@stdlib/constants/float64/half-pi]: one half times the mathematical constant π.
- [`HIGH_WORD_EXPONENT_MASK`][@stdlib/constants/float64/high-word-exponent-mask]: high word mask for the exponent of a double-precision floating-point number.
- [`HIGH_WORD_SIGNIFICAND_MASK`][@stdlib/constants/float64/high-word-significand-mask]: high word mask for the significand of a double-precision floating-point number.
- [`LN_HALF`][@stdlib/constants/float64/ln-half]: natural logarithm of `1/2`.
- [`LN_PI`][@stdlib/constants/float64/ln-pi]: natural logarithm of the mathematical constant π.
- [`LN_SQRT_TWO_PI`][@stdlib/constants/float64/ln-sqrt-two-pi]: natural logarithm of the square root of 2π.
- [`LN10`][@stdlib/constants/float64/ln-ten]: natural logarithm of `10`.
- [`LN_TWO_PI`][@stdlib/constants/float64/ln-two-pi]: natural logarithm of `2π`.
- [`LN2`][@stdlib/constants/float64/ln-two]: natural logarithm of `2`.
- [`LOG10E`][@stdlib/constants/float64/log10-e]: base 10 logarithm of the mathematical constant _e_.
- [`LOG2E`][@stdlib/constants/float64/log2-e]: base 2 logarithm of the mathematical constant _e_.
- [`MAX_BASE10_EXPONENT_SUBNORMAL`][@stdlib/constants/float64/max-base10-exponent-subnormal]: the maximum base 10 exponent for a subnormal double-precision floating-point number.
- [`MAX_BASE10_EXPONENT`][@stdlib/constants/float64/max-base10-exponent]: the maximum base 10 exponent for a double-precision floating-point number.
- [`MAX_BASE2_EXPONENT_SUBNORMAL`][@stdlib/constants/float64/max-base2-exponent-subnormal]: the maximum biased base 2 exponent for a subnormal double-precision floating-point number.
- [`MAX_BASE2_EXPONENT`][@stdlib/constants/float64/max-base2-exponent]: the maximum biased base 2 exponent for a double-precision floating-point number.
- [`MAX_LN`][@stdlib/constants/float64/max-ln]: natural logarithm of the maximum double-precision floating-point number.
- [`MAX_SAFE_FIBONACCI`][@stdlib/constants/float64/max-safe-fibonacci]: maximum safe Fibonacci number when stored in double-precision floating-point format.
- [`MAX_SAFE_INTEGER`][@stdlib/constants/float64/max-safe-integer]: maximum safe double-precision floating-point integer.
- [`MAX_SAFE_LUCAS`][@stdlib/constants/float64/max-safe-lucas]: maximum safe Lucas number when stored in double-precision floating-point format.
- [`MAX_SAFE_NTH_FIBONACCI`][@stdlib/constants/float64/max-safe-nth-fibonacci]: maximum safe nth Fibonacci number when stored in double-precision floating-point format.
- [`MAX_SAFE_NTH_LUCAS`][@stdlib/constants/float64/max-safe-nth-lucas]: maximum safe nth Lucas number when stored in double-precision floating-point format.
- [`MAX`][@stdlib/constants/float64/max]: maximum double-precision floating-point number.
- [`MIN_BASE10_EXPONENT_SUBNORMAL`][@stdlib/constants/float64/min-base10-exponent-subnormal]: the minimum base 10 exponent for a subnormal double-precision floating-point number.
- [`MIN_BASE10_EXPONENT`][@stdlib/constants/float64/min-base10-exponent]: the minimum base 10 exponent for a normal double-precision floating-point number.
- [`MIN_BASE2_EXPONENT_SUBNORMAL`][@stdlib/constants/float64/min-base2-exponent-subnormal]: the minimum biased base 2 exponent for a subnormal double-precision floating-point number.
- [`MIN_BASE2_EXPONENT`][@stdlib/constants/float64/min-base2-exponent]: the minimum biased base 2 exponent for a normal double-precision floating-point number.
- [`MIN_LN`][@stdlib/constants/float64/min-ln]: natural logarithm of the smallest **normalized** double-precision floating-point number.
- [`MIN_SAFE_INTEGER`][@stdlib/constants/float64/min-safe-integer]: minimum safe double-precision floating-point integer.
- [`NINF`][@stdlib/constants/float64/ninf]: double-precision floating-point negative infinity.
- [`NUM_BYTES`][@stdlib/constants/float64/num-bytes]: size (in bytes) of a double-precision floating-point number.
- [`PHI`][@stdlib/constants/float64/phi]: golden ratio.
- [`PI_SQUARED`][@stdlib/constants/float64/pi-squared]: π².
- [`PI`][@stdlib/constants/float64/pi]: the mathematical constant π.
- [`PINF`][@stdlib/constants/float64/pinf]: double-precision floating-point positive infinity.
- [`PRECISION`][@stdlib/constants/float64/precision]: effective number of bits in the significand of a double-precision floating-point number.
- [`SMALLEST_NORMAL`][@stdlib/constants/float64/smallest-normal]: smallest positive **normalized** double-precision floating-point number.
- [`SMALLEST_SUBNORMAL`][@stdlib/constants/float64/smallest-subnormal]: smallest positive **denormalized** double-precision floating-point number.
- [`SQRT_EPS`][@stdlib/constants/float64/sqrt-eps]: square root of double-precision floating-point epsilon.
- [`SQRT_HALF_PI`][@stdlib/constants/float64/sqrt-half-pi]: square root of the mathematical constant π divided by 2.
- [`SQRT_HALF`][@stdlib/constants/float64/sqrt-half]: square root of `1/2`.
- [`SQRT_PHI`][@stdlib/constants/float64/sqrt-phi]: square root of the Golden ratio (φ).
- [`SQRT_PI`][@stdlib/constants/float64/sqrt-pi]: square root of the mathematical constant π.
- [`SQRT_THREE`][@stdlib/constants/float64/sqrt-three]: square root of `3`.
- [`SQRT_TWO_PI`][@stdlib/constants/float64/sqrt-two-pi]: square root of the mathematical constant π times 2.
- [`SQRT_TWO`][@stdlib/constants/float64/sqrt-two]: square root of `2`.
- [`TWO_PI`][@stdlib/constants/float64/two-pi]: the mathematical constant π times 2.
## Examples
```javascript
var objectKeys = require( '@stdlib/utils/keys' );
var constants = require( '@stdlib/constants/float64' );
console.log( objectKeys( constants ) );
```
[@stdlib/constants/float64/apery]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/apery
[@stdlib/constants/float64/catalan]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/catalan
[@stdlib/constants/float64/cbrt-eps]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/cbrt-eps
[@stdlib/constants/float64/e]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/e
[@stdlib/constants/float64/eps]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/eps
[@stdlib/constants/float64/eulergamma]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/eulergamma
[@stdlib/constants/float64/exponent-bias]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/exponent-bias
[@stdlib/constants/float64/fourth-pi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/fourth-pi
[@stdlib/constants/float64/fourth-root-eps]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/fourth-root-eps
[@stdlib/constants/float64/gamma-lanczos-g]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/gamma-lanczos-g
[@stdlib/constants/float64/glaisher-kinkelin]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/glaisher-kinkelin
[@stdlib/constants/float64/half-ln-two]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/half-ln-two
[@stdlib/constants/float64/half-pi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/half-pi
[@stdlib/constants/float64/high-word-exponent-mask]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/high-word-exponent-mask
[@stdlib/constants/float64/high-word-significand-mask]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/high-word-significand-mask
[@stdlib/constants/float64/ln-half]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/ln-half
[@stdlib/constants/float64/ln-pi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/ln-pi
[@stdlib/constants/float64/ln-sqrt-two-pi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/ln-sqrt-two-pi
[@stdlib/constants/float64/ln-ten]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/ln-ten
[@stdlib/constants/float64/ln-two-pi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/ln-two-pi
[@stdlib/constants/float64/ln-two]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/ln-two
[@stdlib/constants/float64/log10-e]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/log10-e
[@stdlib/constants/float64/log2-e]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/log2-e
[@stdlib/constants/float64/max-base10-exponent-subnormal]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max-base10-exponent-subnormal
[@stdlib/constants/float64/max-base10-exponent]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max-base10-exponent
[@stdlib/constants/float64/max-base2-exponent-subnormal]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max-base2-exponent-subnormal
[@stdlib/constants/float64/max-base2-exponent]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max-base2-exponent
[@stdlib/constants/float64/max-ln]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max-ln
[@stdlib/constants/float64/max-safe-fibonacci]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max-safe-fibonacci
[@stdlib/constants/float64/max-safe-integer]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max-safe-integer
[@stdlib/constants/float64/max-safe-lucas]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max-safe-lucas
[@stdlib/constants/float64/max-safe-nth-fibonacci]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max-safe-nth-fibonacci
[@stdlib/constants/float64/max-safe-nth-lucas]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max-safe-nth-lucas
[@stdlib/constants/float64/max]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/max
[@stdlib/constants/float64/min-base10-exponent-subnormal]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/min-base10-exponent-subnormal
[@stdlib/constants/float64/min-base10-exponent]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/min-base10-exponent
[@stdlib/constants/float64/min-base2-exponent-subnormal]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/min-base2-exponent-subnormal
[@stdlib/constants/float64/min-base2-exponent]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/min-base2-exponent
[@stdlib/constants/float64/min-ln]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/min-ln
[@stdlib/constants/float64/min-safe-integer]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/min-safe-integer
[@stdlib/constants/float64/ninf]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/ninf
[@stdlib/constants/float64/num-bytes]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/num-bytes
[@stdlib/constants/float64/phi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/phi
[@stdlib/constants/float64/pi-squared]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/pi-squared
[@stdlib/constants/float64/pi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/pi
[@stdlib/constants/float64/pinf]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/pinf
[@stdlib/constants/float64/precision]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/precision
[@stdlib/constants/float64/smallest-normal]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/smallest-normal
[@stdlib/constants/float64/smallest-subnormal]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/smallest-subnormal
[@stdlib/constants/float64/sqrt-eps]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/sqrt-eps
[@stdlib/constants/float64/sqrt-half-pi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/sqrt-half-pi
[@stdlib/constants/float64/sqrt-half]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/sqrt-half
[@stdlib/constants/float64/sqrt-phi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/sqrt-phi
[@stdlib/constants/float64/sqrt-pi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/sqrt-pi
[@stdlib/constants/float64/sqrt-three]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/sqrt-three
[@stdlib/constants/float64/sqrt-two-pi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/sqrt-two-pi
[@stdlib/constants/float64/sqrt-two]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/sqrt-two
[@stdlib/constants/float64/two-pi]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/two-pi