/**
* ...
* @author Thi
* Graph v. 1.65 / 2.0
*
*
* some expresison samples:
* 0 + 1 - 2 * 3 / 4 ^ -5 +6143 = 0
* -1 ^ round (x) - sin (x) + asin(x²) + (.08x² + .1x - 1)
*
* pi = PI = 3.1415
* e = E = 2.7182
* round (x), floor (x), ceil (x)
* log (x), exp (x)
* sen (x) = seno (x) = sin (x)
* cosseno (x) = cos (x)
* tangente (x) = tangent (x) = tgt (x) = tg (x) = tan (x)
* absoluto (x) = modulo (x) = abs (x)
* aleatorio = random, 0 <= random > 1
* raiz (x) = sqrt (x) = x ^ (1/2)
* acos (x), asin (x), atan (x)
*
*
* The calculator works using 3 main functions:
* - Translate the string to an array, so it can be read
* - Arranje it using Reverse Polish Notation (RPN)
* - Return the value
* We do this for 465 x points for each function for each graph!
*/