https://github.com/espadrine/precision-calculator

https://github.com/espadrine/precision-calculator

Last synced: 10 days ago
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• Host: GitHub
• URL: https://github.com/espadrine/precision-calculator
• Owner: espadrine
• Created: 2021-04-11T22:44:13.000Z (over 3 years ago)
• Default Branch: master
• Last Pushed: 2021-04-21T17:40:10.000Z (over 3 years ago)
• Last Synced: 2024-11-05T07:51:37.542Z (11 days ago)
• Language: JavaScript
• Size: 36.1 KB
• Stars: 0
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Precision calculator

*An evaluator for mathematical expression with arbitrary precision.  

Browser and Node.js.*

```js

import Calculator from 'precision-calculator';

import mpWasm from 'mp-wasm';

const calc = new Calculator(mpWasm);

calc.mpf.setDefaultPrec(128);

console.log(calc('round(9.995 * 100)').result[0]);

// → 1000

```

[Example use in a blog article](https://espadrine.github.io/blog/posts/mean-range-of-bell-curve-distributions.html).

**Under the covers:**

- [MPFR][]: a C library for fast arbitrary-precision algorithms.

- [mp-wasm][]: an [MPFR][] compilation into [WASM][].

- A custom, well-tested parser with clear error messages.

- A tree evaluator.

[MPFR]: https://www.mpfr.org

[mp-wasm]: https://github.com/cag/mp-wasm

[WASM]: https://webassembly.org

## Language

Numbers are as usual: `3.1415`, `1E-15`, `2_900_000`.

Operators include `+`, `-`, `*`, `×`, `/`, `÷`, `%` (modulo), `^` and `**`

(power), and `!` for factorials (which support any real number).

The following functions are also supported:

`rootn`, `dim`, `atan2`, `gammaInc`, `beta`, `jn`, `yn`, `agm`, `hypot`, `fmod`,

`remainder`, `min`, `max`, `sqr`, `sqrt`, `recSqrt`, `cbrt`, `neg`, `abs`,

`log`, `ln`, `log2`, `log10`, `log1p`, `exp`, `exp2`, `exp10`, `expm1`, `cos`,

`sin`, `tan`, `sec`, `csc`, `cot`, `acos`, `asin`, `atan`, `cosh`, `sinh`,

`tanh`, `sech`, `csch`, `coth`, `acosh`, `asinh`, `atanh`, `eint`, `li2`,

`gamma`, `lngamma`, `digamma`, `zeta`, `erf`, `erfc`, `j0`, `j1`, `y0`, `y1`,

`rint`, `ceil`, `rintCeil`, `floor`, `rintFloor`, `round`, `rintRound`,

`rintRoundeven`, `trunc`, `rintTrunc`, `frac`.

The syntax also supports lists, such as `(1, 2)`,

to handle multiple computations at once.

Computation results are lists.

## API

### `new Calculator(mpWasm)`

The main, default export, is a class which must be initialized.

It includes a [`.mpf`][mp-wasm] object so that the precision can, in particular,

be set.

### `Calculator.prototype.compute(expression)`

The computation takes a String expression, eg. `"round(9.995 * 100)"`.

It returns an Object with the following fields:

- `result`: a list of [MPFRFloat][mp-wasm] numbers.

- `tree`: the abstract syntax tree representation of the input.

- `errors`: a list of SyntaxTreeError found while parsing or evaluating the

  input.

#### `SyntaxTreeError`

The errors have the following fields:

- `message` describing the error,

- `line` at which the error occured in the String expression (1-indexed),

- `column` (1-indexed).

- `.toString()`: lays out the error in a readable form.

#### `SyntaxTree`

It exports a `.toString()` function which allows convenient introspection of the

abstract syntax tree.

### `Calculator.prototype.parse(expression)`

If you only wish to perform parsing, this will not do the computation.

It works the same way as `.compute()`, but returns only this:

- `tree`: the abstract syntax tree representation of the input.

- `errors`: a list of errors in parsing or evaluating the input.