Overflow in exp in scipy/numpy in Python?

Question

What does the following error:

Warning: overflow encountered in exp

in scipy/numpy using Python generally mean? I\'m computing a ratio in log

Answer 1

Isn't exp(log(a) - log(b)) the same as exp(log(a/b)) which is the same as a/b?

>>> from math import exp, log
>>> exp(log(100) - log(10))
10.000000000000002
>>> exp(log(1000) - log(10))
99.999999999999957

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2010-12-07: If this is so "some values in the array b are intentionally set to 0", then you are essentially dividing by 0. That sounds like a problem.