## kalk

A math evaluator library that supports user-defined functions, variables and units, and can handle fairly ambiguous syntax

### 43 releases(27 stable)

 3.2.0 Apr 3, 2024 Mar 23, 2024 Jul 20, 2023 Jan 24, 2023 Jun 18, 2020

#549 in Parser implementations

Used in 2 crates

MIT and LGPL-3.0+

320KB
8K SLoC

# kalk

Kalk is a math parser library that supports user-defined variables and functions. An example of what it can parse:

``````f(x, y) = sum(1, 3, (2sin4/x!)^y) + cos(n deg)
a = 3
f(a, 2)
``````

`>> 1.1899401098014355`

## Features

• Operators: `+`, `-`, `*`, `/`, `!`
• Groups: `()`, `[]`, `⌈ceil⌉`, `⌊floor⌋`
• Vectors: (x, y, z, ...)
• Matrices: [x, y, z; a, b, c; ...]
• Pre-defined functions and constants
• User-defined functions and variables. `f(x, y) = xy`, `x = 5`
• Root finding using Newton's method (eg. x^2 = 64). Note: estimation and limited to one root
• Derivative of functions (derivatives of noisy functions or of higher order can be a bit inaccurate). `f'(2)`, `sin'(-pi)`
• Integration. `∫(0, pi, sin(x) dx)` or `∫(0, π, sin(x) dx)`, maybe sometimes be slightly off
• Understands fairly ambiguous syntax. Eg. `2sin50 + 2xy`
• Sum function: `sum(start, to, expression)` Eg. `sum(1, 3, 2n+1)` is the same as `2*1+1 + 2*2+1 + 2*3+1` = `15`
• Piecewise functions: `f(x) = { f(x + 1) if x <= 1; x otherwise }`, pressing enter before typing the final `}` will make a new line without submitting
• Different number bases: Either with a format like `0b1101`, `0o5.3`, `0xff` or a format like `1101_2`. The latter does not support letters, as they would be interpreted as variables
• Misc: separate expressions by a semicolon to write them on the same line, use the `ans` variable to get the value of the previously calculated expression

## Rust Usage

``````use kalk::parser;
let mut parser_context = parser::Context::new();
let precision = 53;
let result = parser::eval(&mut parser_context, "5*3", precision).unwrap().unwrap();
assert_eq!(result.to_f64(), 15f64);
``````

### Using f64 instead of rug::Float

The cargo feature `rug` enables rug, and is used by default. If you disable this, kalk will use `f64` instead, making it more portable.

### Compiling

Make sure you have `diffutils` `gcc` `make` and `m4` installed.

## JavaScript Usage

``````const kalk = await import("@paddim8/kalk");
const context = new kalk.Context();
console.log(context.evaluate("2pi + 3").toScientificNotation().toString());
``````

~4MB
~75K SLoC