reverse_polish.py

from math import sin, cos, tan, radians, pi, e, log

inp = 'e 2 ^ ln 3 * 60 cos 8 * + 4 0.5 ^ 3 * 1 - /'.split(' ')
stack = []

operators = {
    '+': (2, lambda j, k: j + k),
    '-': (2, lambda j, k: j - k),
    '*': (2, lambda j, k: j * k),
    '/': (2, lambda j, k: j / k),
    '^': (2, lambda j, k: j ** k),
    'sin': (1, lambda j: sin(radians(j))),
    'cos': (1, lambda j: cos(radians(j))),
    'tan': (1, lambda j: tan(radians(j))),
    'ln': (1, lambda j: log(j)),
    'e': (0, lambda: e),
    'pi': (0, lambda: pi)
}

while inp:
    try:
        i = float(inp[0])
        num = True
    except ValueError:
        i = inp[0]
        num = False
    if num:
        stack.append(i)
    else:
        o = operators[i]
        nums = []
        for n in range(o[0]):
            nums.insert(0, stack.pop())
        stack.append( o[1](*nums) )
    inp.remove(inp[0])

print(stack[0])

http://users.ece.gatech.edu/mleach/revpol/

Currently powers should be written like this: base exponent ^