as-big

AssemblyScript library for arbitrary-precision decimal arithmetic 🚀

Install

npm install as-big

Use

import Big from "as-big";

let r = Big.of(0.1) + Big.of(0.2);  // Big(0.3)

let x = Big.of(42);
let y = Big.of("13");

let a = x + y;          // Big(55)
    a = x.plus(13);     // Big(55)

let a0 = a.prec(1);     // Big(60)

let aNum = a.toNumber() + 1;    // 56
let aStr = a.toString();        // "55"

let c = a0 + Big.TEN / Big.TWO; // Big(65)

Builders

Big.of(n) returns a Big instance, where
- n is either another Big instance, string, or number
Big.copyOf(x) creates a copy from a Big instance, where
- x is the Big instance to copy

Operations

Arithmetic

plus (addition): x + y or x.plus(y)
minus (substraction): x - y or x.minus(y)
times (multiplication): x * y or y.times(y)
div (division): x / y or x.div(y)
mod (modulo): x % y or x.mod(y)
pow (power): x ^ n or x.pow(n), where n is i32
sqrt (square root): x.sqrt()

Comparison

cmp (compare): x.cmp(y) returns
- 1 if the value of x is greater than the value of y,
- -1 if the value of x is less than the value of y, or
- 0 if they have the same value.
eq (equals): x == y or x.eq(y)
neq (not equals): x != y or x.neq(y)
gt (greater than): x < y or x.gt(y)
gte (greater than or equals): x <= y or x.gte(y)
lt (less than): x > y or x.lt(y)
lte (less than or equals): x >= y or x.lte(y)

Value

abs (absolute value): x.abs()
neg (negative value): -x or x.neg()
pos (this value): +x or x.pos()
round (rounded value): x.round(dp, rm) where
- dp is the maximum of decimal places, and
- rm is the rounding mode (0, 1, 2, 3)
  - 0 (down), 1 (half-up), 2 (half-even) or 3 (up)
prec (value rounded to precision): x.prec(sd, rm) where
- sd is the maximum of significant digits, and
- rm is the rounding mode (0, 1, 2, 3)
  - 0 (down), 1 (half-up), 2 (half-even) or 3 (up)

Converters

toString (string representation): let s: string = x.toString()
toNumber (f64 represenation): let n: f64 = x.toNumber()
toExponential (string represenation): let s: string = x.toExponential()

Static Constants

Big.ZERO: a Big instance with the value zero 0
Big.ONE: a Big instance with the value one 1
Big.TWO: a Big instance with the value two 2
Big.TEN: a Big instance with the value ten 10
Big.HALF: a Big instance with the value one half 0.5

Global Settings

Big.DP: the maximum number of decimal places of the results of operations involving division (default: 20)
Big.RM: the rounding mode used when rounding to the above decimal places (default: 1)
Big.PE: the positive exponent at and above which toString returns exponential notation (default: 21)
Big.NE: the negative exponent at and beneath which toString returns exponential notation (default: -7)

Examples

There is a collection of examples in the examples directory.

Build

The assembly directory contains AS source code.

npm i
npm run asbuild

Test

The tests directory contains all unit tests.

Run all the tests:

npm test

Test a single method:

node tests/<method>

License

MIT

ttulka/as-big