On Wed, 17 Feb 2010 08:19:00 am David DiCato wrote: > 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.
What's the justification for that convention? It seems wrong to me. If you expand out hypot and substitute a=inf and b=nan, you get: >>> math.sqrt(inf*inf + nan*nan) nan which agrees with my pencil-and-paper calculation: sqrt(inf*inf + nan*nan) = sqrt(inf + nan) = sqrt(nan) = nan -- Steven D'Aprano _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com