flerokoo / pi-walks-into-a-bar

Math expression evaluator

π walks into a bar

Evaluator of mathmetical expressions.

Converts given mathematical expression in infix notation to reverse polish notation using Shunting-yard algorithm and evaluates it with specified variables and functions.

Tokenization is performed using my other module tokenizer2000

Why?

See Why? section of the tokenizer2000. Also to impress girls (lol)

Usage

No one will ever use this, but nonetheless:

let parse = require("pi-walks-into-a-bar");

let result = parse("2*sin(pi/2) + 5**(2*ctg(x))").evaluate([
    {
        type: "function",
        name: "sin",
        length: 1,
        execute: arg => Math.sin(arg)
    },
    {
        type: "function",
        name: "cos",
        length: 1,
        execute: arg => Math.cos(arg)
    },
    {
        type: "function",
        name: "tan",
        length: 1,
        execute: arg => Math.tan(arg)
    },
    {
        type: "function",
        name: "ctg",
        length: 1,
        execute: arg => 1/Math.tan(arg)
    },
    {
        type: "variable",
        name: "pi",
        value: Math.PI
    },
    {
        type: "variable",
        name: "e",
        value: Math.exp(1)
    },
    {
        type: "variable",
        name: "x",
        value: 2
    },
    
]);