Status: Accepted
Owner: asmeurer
Labels: Type-Defect Priority-Medium
New issue 2003 by asmeurer: Use factorint() with limit argument in
sympy/core/numbers.py
http://code.google.com/p/sympy/issues/detail?id=2003
Based on this thread:
http://groups.google.com/group/sympy/browse_thread/thread/86d45d70f580d5de
There is these lines in Integer._eval_power():
# The following is an algorithm where we collect perfect roots
# from the factors of base
if b > 4294967296:
# Prevent from factorizing too big integers
return None
Which are well intentioned, because factoring large numbers can be
extremely expensive (exponential) if you send the wrong numbers. But there
is a limit option to factorint() that lets you only factor out small
integers, no matter how large the original integer is. So I think we
should do that instead, because factoring large numbers is *not* expensive
if all the factors are small.
Also, I noticed that Intger.factors() is using its own factoring algorithm
instead of the Pollard-Rho in factorint(). So that needs to be fixed too.
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