RPN calculator

The input must be in the form of: example: {res = 23 42 +}

Defined numbers: Pi, log2e, log10e, ln2, ln1, e.
Single argument functions: sqrt, cbrt, sin, cos, tan, asin, acos, atan, asinh, acosh, atanh, sinh, cosh, tanh
log, log10, log1p, log2, exp

Two argument functions: atan2 (y, x), pow (x, y)
example: {res = 30 sin} {res = 2 8 pow}