Python math domain error when using pow

Question

Here is the code:

exp = 1.79
def calc(t):
    return pow(t - 1, exp)

The input values of t range from 0 to 1 (e.g. 0.04). This code throws a "math domain exception," but I'm not sure why.

How can I solve this?

Answer 1

If t ranges from 0 to 1, then t - 1 ranges from -1 to 0. Negative numbers cannot be raised to a fractional power, neither by pow builtin nor math.pow.

Answer 2

Negative numbers raised to a fractional exponent do not result in real numbers. You will have to use cmath if you insist on calculating and using them, but note that you will need some experience in complex numbers in order to make use of the result.

>>> cmath.exp(cmath.log(0.04 - 1) * 1.79)
(0.7344763337664206-0.5697182434534497j)