Math expression calculator. Evaluate an arithmetic expression safely (parsed, never executed as code): + - * / % ^ and **, parentheses, factorial !, constants pi, e and tau, and functions sqrt, cbrt, abs, round, floor, ceil, exp, ln, log (base 10), log2, sin, cos, tan, asin, acos, atan (radians), min, max and pow. Up to 500 characters. Use when an agent needs exact arithmetic instead of guessing, for prices, unit maths or formulas.