math

Documentation

Index

• Constants
• func ExpBySquaring(base big.Int, n int64) big.Int
• func ExpNeg(x *big.Int) *big.Int
• func Ln(z big.Int) big.Int
• func Parse(coefs []string) []*big.Int
• func Polyval(p []*big.Int, x *big.Int) *big.Int

Constants

const Precision128 = 128

note: all coefficients for which Polyval is used would need to be updated if this precision changes

Functions

func ExpBySquaring

func ExpBySquaring(base big.Int, n int64) big.Int

ExpBySquaring takes a Q.128 base b and an int64 exponent n and computes n^b using the exponentiation by squaring method, returning a Q.128 value.

func ExpNeg

func ExpNeg(x *big.Int) *big.Int

ExpNeg accepts x in Q.128 format and computes e^-x. It is most precise within [0, 1.725) range, where error is less than 3.4e-30. Over the [0, 5) range its error is less than 4.6e-15. Output is in Q.128 format.

func Ln

func Ln(z big.Int) big.Int

The natural log of Q.128 x.

func Parse

func Parse(coefs []string) []*big.Int

Parse a slice of strings (representing integers in decimal) Convention: this function is to be applied to strings representing Q.128 fixed-point numbers, and thus returns numbers in binary Q.128 representation

func Polyval

func Polyval(p []*big.Int, x *big.Int) *big.Int

polyval evaluates a polynomial given by coefficients `p` in Q.128 format at point `x` in Q.128 format. Output is in Q.128. Coefficients should be ordered from the highest order coefficient to the lowest.