decimal

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Published: Feb 21, 2017 License: Apache-2.0 Imports: 7 Imported by: 0

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Constants

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const Precision = 16

Precision defines the minimum precision all inexact decimal calculations should attempt to achieve.

Variables

This section is empty.

Functions

func Cbrt

func Cbrt(z, x *inf.Dec, s inf.Scale) *inf.Dec

Cbrt calculates the cube root of x to the specified scale and stores the result in z, which is also the return value.

The cube root calculation is implemented using Newton-Raphson method. We start with an initial estimate for cbrt(d), and then iterate:

x_{n+1} = 1/3 * ( 2 * x_n + (d / x_n / x_n) ).

func Exp

func Exp(z, n *inf.Dec, s inf.Scale) *inf.Dec

Exp computes (e^n) (where n = a*b with a being an integer and b < 1) to the specified scale and stores the result in z, which is also the return value.

func Float64FromDec

func Float64FromDec(dec *inf.Dec) (float64, error)

Float64FromDec converts a decimal to a float64 value, returning the value and any error that occurred. This converson exposes a possible loss of information.

func Log

func Log(z *inf.Dec, x *inf.Dec, s inf.Scale) (*inf.Dec, error)

Log computes the natural log of x using the Taylor series to the specified scale and stores the result in z, which is also the return value. The function will return an error if x is a negative number.

func Log10

func Log10(z *inf.Dec, x *inf.Dec, s inf.Scale) (*inf.Dec, error)

Log10 computes the log of x with base 10 to the specified scale and stores the result in z, which is also the return value. The function will panic if x is a negative number.

func LogN

func LogN(z *inf.Dec, x *inf.Dec, n *inf.Dec, s inf.Scale) (*inf.Dec, error)

LogN computes the log of x with base n to the specified scale and stores the result in z, which is also the return value. The function will panic if x is a negative number or if n is a negative number.

func Mod

func Mod(z, x, y *inf.Dec) *inf.Dec

Mod performs the modulo arithmatic x % y and stores the result in z, which is also the return value. It is valid for z to be nil, in which case it will be allocated internally. Mod will panic if the y is zero.

The modulo calculation is implemented using the algorithm:

x % y = x - (y * ⌊x / y⌋).

func NewDecFromFloat

func NewDecFromFloat(f float64) *inf.Dec

NewDecFromFloat allocates and returns a new Dec set to the given float64 value. The function will panic if the float is NaN or ±Inf.

func NumDigits

func NumDigits(bi *big.Int, tmp []byte) (int, []byte)

NumDigits returns the number of decimal digits that make up big.Int value. The function first attempts to look this digit count up in the digitsLookupTable. If the value is not there, it defaults to constructing a string value for the big.Int and using this to determine the number of digits. If a string value is constructed, it will be returned so it can be used again.

func Pow

func Pow(z, x, y *inf.Dec, s inf.Scale) (*inf.Dec, error)

Pow computes (x^y) as e^(y ln x) to the specified scale and stores the result in z, which is also the return value. If y is not an integer and x is negative an error is returned. If x is zero and y is negative an error is returned.

func PowerOfTenDec

func PowerOfTenDec(pow int) *inf.Dec

PowerOfTenDec returns an *inf.Dec with the value 10^pow. It should be treated as immutable.

Non-negative powers of 10 will have their value represented in their underlying big.Int with a scale of 0, while negative powers of 10 will have their value represented in their scale with a big.Int value of 1.

func PowerOfTenInt

func PowerOfTenInt(pow int) *big.Int

PowerOfTenInt returns a *big.Int with the value 10^pow. It should be treated as immutable.

func SetFromFloat

func SetFromFloat(z *inf.Dec, f float64) *inf.Dec

SetFromFloat sets z to the given float64 value and returns z. The function will panic if the float is NaN or ±Inf.

func Sqrt

func Sqrt(z, x *inf.Dec, s inf.Scale) *inf.Dec

Sqrt calculates the square root of x to the specified scale and stores the result in z, which is also the return value. The function will panic if x is a negative number.

The square root calculation is implemented using Newton's Method. We start with an initial estimate for sqrt(d), and then iterate:

x_{n+1} = 1/2 * ( x_n + (d / x_n) ).

Types

This section is empty.

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