Parser of Expression Grammar can take a string with an expression using RPN and parse it to evaluate its result.Constants, functions, operators, custom functions and custom operators, are supported.Requirements: PHP 4.2.3 or higher

Mathematical expressions with operands and operators in reverse Polish can be parsed and evaluated. If the expression is split in multiple lines, it can evaluate each line individually.Currently Simple RPN Interpretersupports the operators: +, - , *, /, IF, THEN, SWAP, DUP, =, <>, >, <. >= and <= .Requirements: PHP 4.0.0 or higher