Use the math
module instead of the cmath
module; the latter is for complex numbers only:
>>> import math
>>> print math.sqrt(25)
5.0
For what it’s worth, the cmath
result is correct, if you expected a complex number. You could take just the .real
component of the result, but since there is a regular floating point equivalent in the math
module there is no point in having your computer do the extra work.