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https://github.com/polywrap/as-bignumber

An AssemblyScript class for math with arbitrary-precision decimal and integer numbers
https://github.com/polywrap/as-bignumber

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An AssemblyScript class for math with arbitrary-precision decimal and integer numbers

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# BigNumber

BigNumber is an AssemblyScript class for math with arbitrary-precision decimal and integer numbers



## Features



- Fast arithmetic operations

- Lightweight

- Immutable instances

- Core operations thoroughly tested



## Getting Started



### Installation

`npm install as-bignumber`  

or  

`yarn add as-bignumber`



### Quick start



```typescript

import { BigNumber } from "as-fraction"



// generic constructor supports string, BigInt, f32, f64, and all native integer types

const a: BigNumber = BigNumber.from("1.93");

// construct from string

const b: BigNumber = BigNumber.fromString("1.93");

// construct from BigInt

const c: BigNumber = BigNumber.fromBigInt(BigInt.from("3"));

// construct from fraction components

const d: BigNumber = BigNumber.fromFraction(BigInt.from("1"), BigInt.from("3"))



// arithmetic (operator overloads: +, -, *, /, **)

const sum: BigNumber = a.add(b);

const difference: BigNumber = a.sub(b);

const product: BigNumber = a.mul(b);

const quotient: BigNumber = a.div(b);

const exponential: BigNumber = a.pow(3);

const squared: BigNumber = a.square();

const squareRoot: BigNumber = a.sqrt();



// comparison operations (operator overloads: ==, !=, <, <=, >, >=)

const isEqual: boolean = a.eq(b);

const isNotEqual: boolean = a.ne(b);

const isLessThan: boolean = a.lt(b);

const isLessThanOrEqualTo: boolean = a.lte(b);

const isGreaterThan: boolean = a.gt(b);

const isGreaterThanOrEqualTo: boolean = a.gte(b);



// binary arithmetic and comparison operators also have static implementations

const staticProduct: BigNumber = BigNumber.mul(a, b);

const staticIsEqual: boolean = BigNumber.eq(a, b);



// instantiate new copy, absolute value, opposite, or reciprocal

const sameNumber: BigNumber = a.copy();

const positiveNumber: BigNumber = a.abs();

const oppositeSign: BigNumber = a.opposite();

const reciprocal: BigNumber = a.reciprocal();



// convenience functions

const isNegative: boolean = a.isNegative;

const isInteger: boolean = a.isInteger;

const isZeroNumber: boolean = a.isZero();

const one: BigNumber = BigNumber.ONE;

const half: BigNumber = BigNumber.HALF;



// string output

const toString: string = a.toString();

const toSignificant: string = a.toSignificant(digits, rounding);

const toFixed: string = a.toFixed(places, rounding);



// type conversions

const toBigNumber: BigNumber = a.toBigNumber();

const toBigInt: BigInt = a.toBigInt();

const toFloat: f64 = a.toFloat64();



export enum Rounding {

  UP, // Rounding mode to round away from zero.

  DOWN, // Rounding mode to round towards zero.

  CEIL, // Rounding mode to round towards positive infinity.

  FLOOR, // Rounding mode to round towards negative infinity.

  HALF_UP, // Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up.

  HALF_DOWN, // Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down.

  HALF_EVEN, // Rounding mode to round towards the "nearest neighbor" unless both neighbors are equidistant, in which case, round towards the even neighbor.

  NONE, // Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary.

}

```

### Rounding and Precision



Because some numbers are irrational or have infinite digits, rounding is sometimes necessary. Numbers are rounded to a 

specific number of digits, which we call 'precision'. For example, the number 123.45 has five digits, and therefore has 

a precision of 5.



By default, numbers are assigned a maximum precision of 155 for some operations. When a result of one of these 

operations would exceed 155 digits, it is rounded to the best 155 digits according to the default or specified rounding 

rule. The magnitude of a number can still exceed that of a 155 digit integer due to exponential notation.



Arithmetic operations--and other methods that may require rounding--accept optional arguments to specify the precision 

and rounding mode for the result of the operation. 



The default precision and rounding mode can be changed using static methods.



A precision less than or equal to 0 indicates that the that number has exact precision, or that the result of an 

arithmetic operation should have exact precision. This can cause operations to throw an exception when a result would 

have infinite digits.



```typescript

// rounding modes

export enum Rounding {

  UP, // Rounding mode to round away from zero.

  DOWN, // Rounding mode to round towards zero.

  CEIL, // Rounding mode to round towards positive infinity.

  FLOOR, // Rounding mode to round towards negative infinity.

  HALF_UP, // Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up.

  HALF_DOWN, // Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down.

  HALF_EVEN, // Rounding mode to round towards the "nearest neighbor" unless both neighbors are equidistant, in which case, round towards the even neighbor.

  NONE, // Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary.

}



// many methods accept arguments that adjust precision and rounding

const precision: i32 = 250;

const rounding: Rounding = Rounding.FLOOR;

const quotient: BigNumber = a.div(b, precision, rounding);



// default precision and rounding can be changed

BigNumber.DEFAULT_PRECISION = 155;

BigNumber.DEFAULT_ROUNDING = Rounding.HALF_UP;

```



## Contributing  



### Build  

`yarn build`  



### Test  

`yarn test`  



### Lint

`yarn lint`



To autofix lint errors:

`yarn lint:fix`



## Handling integer numbers



If you need to work with arbitrarily large integers, check out as-bigint: https://github.com/polywrap/as-bigint. The BigInt class facilitates high-performance integer arithmetic.



## Handling fractions



If you need to work with numbers represented as fractions, check out as-fraction: https://github.com/polywrap/as-fraction. The Fraction class is built on top of BigInt for high-performance fraction arithmetic.



## Acknowledgements



Polywrap developed BigNumber to use in the development tools we produce for fast, language-agnostic decentralized API development. Polywrap allows developers to interact with any web3 protocol from any language, making between-protocol composition easy. Learn more at https://polywrap.io.



as-BigNumber was influenced by [Java's BigDecimal class](https://github.com/AdoptOpenJDK/openjdk-jdk11/blob/master/src/java.base/share/classes/java/math/BigDecimal.java) and the [as-big package](https://github.com/ttulka/as-big).



## Contact

Please create an issue in this repository or email [email protected]