JavaScript
//+ Jonas Raoni Soares Silva
//@ http://jsfromhell.com/classes/math-processor [rev. #1]
// modified to support get_vars by Amir Shimoni - see bottom
MathProcessor = function(){
var o = this;
o.o = {
"+": function(a, b){ return +a + b; },
"-": function(a, b){ return a - b; },
"%": function(a, b){ return a % b; },
"/": function(a, b){ return a / b; },
"*": function(a, b){ return a * b; },
"^": function(a, b){ return Math.pow(a, b); },
"~": function(a, b){ return Math.sqrt(a, b); }
};
o.s = { "^": 3, "~": 3, "*": 2, "/": 2, "%": 1, "+": 0, "-": 0 };
o.u = {"+": 1, "-": -1}, o.p = {"(": 1, ")": -1};
};
with({p: MathProcessor.prototype}){
p.methods = {
div: function(a, b){ return parseInt(a / b); },
fra: function(a){ return a - parseInt(a); },
sum: function(n1, n2, n3, n){ for(var r = 0, a, l = (a = arguments).length; l; r += a[--l]); return r; },
medium: function(n1, n2, n3, n){ for(var r = 0, a, l = (a = arguments).length; l; r += a[--l]); return r / a.length; }
};
p.parse = function(e){
for(var n, x, _ = this, o = [], s = [x = _.RPN(e.replace(/ /g, "").split(""))]; s.length;)
for((n = s[s.length-1], --s.length); n[2]; o[o.length] = n, s[s.length] = n[3], n = n[2]);
for(; (n = o.pop()) != undefined; n[0] = _.o[n[0]](isNaN(n[2][0]) ? _.f(n[2][0]) : n[2][0], isNaN(n[3][0]) ? _.f(n[3][0]) : n[3][0]));
return +x[0];
};
p.RPN = function(e){
var x, r, _ = this, c = r = [, , , 0];
if(e[0] in _.u || !e.unshift("+"))
for(; e[1] in _.u; e[0] = _.u[e.shift()] * _.u[e[0]] + 1 ? "+" : "-");
(c[3] = [_.u[e.shift()], c, , 0])[1][0] = "*", (r = [, , c, 0])[2][1] = r;
(c[2] = _.v(e))[1] = c;
(!e.length && (r = c)) || (e[0] in _.s && ((c = r)[0] = e.shift(), !e.length && _.error()));
while(e.length){
if(e[0] in _.u){
for(; e[1] in _.u;...