evalRPN("3 4 2 * 1 5 - 2 3 ^ ^ / +") evalRPN(s){ stack := [] out := "For RPN expression: '" s "'`r`n`r`nTOKEN`t`tACTION`t`t`tSTACK`r`n" Loop Parse, s If A_LoopField is number t .= A_LoopField else { If t stack.Insert(t) , out .= t "`tPush num onto top of stack`t" stackShow(stack) "`r`n" , t := "" If InStr("+-/*^", l := A_LoopField) { a := stack.Remove(), b := stack.Remove() stack.Insert( l = "+" ? b + a :l = "-" ? b - a :l = "*" ? b * a :l = "/" ? b / a :l = "^" ? b **a :0 ) out .= l "`tApply op " l " to top of stack`t" stackShow(stack) "`r`n" } } r := stack.Remove() out .= "`r`n The final output value is: '" r "'" clipboard := out return r } StackShow(stack){ for each, value in stack out .= A_Space value return subStr(out, 2) }