php-calculator

A function calculator for PHP using the shunting yard algorithm

How to use

To evaluate a function you use the Calculator class in src/Calculator.php

If you just want to evaluate a function once you can use the following function:

float Calculator::EvaluateExpression(string $expression, string $var, float $value);

This function parses the expression and exchanges the identifier given with $var for $value.

If you want to evaluate the same function but for a lot of different values, it's better to "compile" it to postfix notation first. This can be done with the function:

Expression Calculator::CompileExpression(string $expression, string $var);

This returns an Expression object which contains the expression's tokens in postfix order and the name of the variable.

To evaluate the Expression object with a given value, you use the function

float Calculator::EvaluateCompiledExpression(Expression $expression, float $value);

which returns the value of the expression for the given value.