denissimon/formula-parser

Parsing and evaluating mathematical formulas given as strings.

Formula Parser

, _(*1)

Formula Parser is a library for parsing and evaluating mathematical formulas given as strings., _(*2)

Supports:, _(*3)

• Operators: +, -, *, /, ^
• Variables: x, y, z, a, b
• Numbers with decimal point '.'
• Numbers in E notation
• Constants: pi, e, Inf
• Functions: sqrt, abs, sin, cos, tan, log, exp
• Unlimited nested parentheses
• NaN (Not a Number)

Installation

Requires PHP 5.4 or higher., _(*4)

To install with Composer:, _(*5)

``` sh composer require denissimon/formula-parser, <sub>(*6)</sub>

Usage
-----

``` php
require_once __DIR__ . '/vendor/autoload.php';

use FormulaParser\FormulaParser;

$formula = '3*x^2 - 4*y + 3/y';
$precision = 2; // Number of digits after the decimal point

try {
    $parser = new FormulaParser($formula, $precision);
    $parser->setVariables(['x' => -4, 'y' => 8]);
    $result = $parser->getResult(); // [0 => 'done', 1 => 16.38]
} catch (\Exception $e) {
    echo $e->getMessage(), "\n";
}

The $precision parameter has a default of 4, and it's not required to specify:, <sub>(*7)</sub>

php $parser = new FormulaParser('3+4*2/(1-5)^8'); $result = $parser->getResult(); // [0 => 'done', 1 => 3.0001], <sub>(*8)</sub>

The initialized object $parser has the following methods:, <sub>(*9)</sub>

setValidVariables($array) Overwrites default valid variables., <sub>(*10)</sub>

setVariables($array) Sets variables., <sub>(*11)</sub>

getResult() Returns an array [0 => v1, 1 => v2], where v1 is 'done' or 'error', and v2 is a computed result or validation error message, respectively., <sub>(*12)</sub>

getFormula() Returns the text of the formula passed to the constructor., <sub>(*13)</sub>

More usage examples can be found in tests/FormulaParserTest.php, <sub>(*14)</sub>

License

Licensed under the MIT license, <sub>(*15)</sub>