The C++ Mathematical Expression Library (ExprTk) is a simple to use, easy to integrate and extremely efficient and fast mathematical expression parsing and evaluation engine. The parsing engine supports various kinds of functional, logic processing semantics and is very easily extendible.
http://www.partow.net/programming/exprtk/index.html
Mathematical operators (+, , *, /, %, ^)
Functions (min, max, avg, sum, abs, ceil, floor, round, roundn, exp, log, log10, logn, root, sqrt, clamp, range)
Trigonometry (sin, cos, tan, acos, asin, atan, atan2, cosh, cot, csc, sec, sinh, tanh, d2r, r2d, d2g, g2d, hyp)
Equalities, Inequalities and Assigment (=, ==, <>, !!=, , >=, :=,
30 Day SummaryApr 10 2016 — May 10 2016

12 Month SummaryMay 10 2015 — May 10 2016
