math.decimal #

Description

math.decimal provides arbitrary-precision fixed-point decimal arithmetic. It stores values as an integer coefficient plus a decimal scale, so addition, subtraction, and multiplication stay exact.

Division is exposed through div_prec, which rounds half up to a caller-chosen number of decimal places. The / operator uses decimal.default_division_precision.

Example

import math.decimal

price := decimal.from_string('19.99')!
fee := decimal.from_string('1.50')!
total := price + fee
assert total.str() == '21.49'

share := total.div_prec(decimal.from_int(3), 2)!
assert share.str() == '7.16'

fn from_i64(value i64) Decimal

from_i64 creates a decimal from an i64.

fn from_int(value int) Decimal

from_int creates a decimal from an int.

fn from_string(input string) !Decimal

from_string parses a decimal string without exponent notation.

fn from_u64(value u64) Decimal

from_u64 creates a decimal from a u64.

fn new(coefficient big.Integer, scale int) Decimal

new creates a decimal from coefficient * 10^-scale.

struct Decimal {
	coefficient_value big.Integer
	scale_value       int
}

Decimal represents an arbitrary-precision fixed-point decimal value. Its numeric value is coefficient * 10^-scale.

fn (d Decimal) coefficient() big.Integer

coefficient returns the integer coefficient stored by d.

fn (d Decimal) scale() int

scale returns the number of decimal places stored by d.

fn (d Decimal) is_zero() bool

is_zero returns true when d == 0.

fn (d Decimal) abs() Decimal

abs returns the absolute value of d.

fn (d Decimal) neg() Decimal

neg returns the negated value of d.

fn (d Decimal) str() string

str returns the canonical decimal representation of d.

fn (left Decimal) + (right Decimal) Decimal

• returns the exact sum of left and right.

fn (left Decimal) - (right Decimal) Decimal

• returns the exact difference of left and right.

fn (left Decimal) * (right Decimal) Decimal

• returns the exact product of left and right.

fn (dividend Decimal) / (divisor Decimal) Decimal

/ divides dividend by divisor using default_division_precision.

fn (dividend Decimal) div_prec(divisor Decimal, precision int) !Decimal

div_prec divides dividend by divisor and rounds half up to precision digits after the decimal point.

fn (left Decimal) == (right Decimal) bool

== returns true when left and right represent the same value.

fn (left Decimal) < (right Decimal) bool

< returns true when left is smaller than right.