I have a minor concern about certain corner cases with math.hypot and complex.__abs__, namely when one component is infinite and one is not a number. If we execute the following code: import math inf = float('inf') nan = float('nan') print math.hypot(inf, nan) print abs(complex(nan, inf)) ... then we see that 'inf' is printed in both cases. The standard library tests (for example, test_cmath.py:test_abs()) seem to test for this behavior as well, and FWIW, I personally agree with this convention. However, the math module's documentation for both 2.6 and 3.1 states, "All functions return a quiet NaN if at least one of the args is NaN." math.pow(1.0, nan) is another such exception to the rule. Perhaps the documentation should be updated to reflect this. Thanks, - David