[Numpy-discussion] bug fix for exp()

Frank Gibbons fgibbons at hms.harvard.edu
Mon Oct 7 13:54:06 EDT 2002


I've been lurking for a while, and using Numeric for about 5-6 months. I 
submitted a bug report about two months ago 
regarding incorrect underflow behavior in exp().

I'd really like to get that fixed, nobody else seems to be working on it, 
and so I checked out the CVS tree. From reading the API section of the 
manual, I can see that unary ufuncs are driven by PyUFunc_FromFuncAndData() 
and that exp already has check_return set to 1, so that it should clean up 
rank-0 arrays, and raise the appropriate Python exception when 'errno' is 
set by a math error.

I'd like to take a closer look into things, and one way of doing that would 
be to use a unit-test suite, but it's not obvious where that is (if at all) 
in the source distribution. Is there one?

Another way to look into it would be if I could write some C code, then 
drop into Numeric's code and track what's going on when I call exp() for 
arguments that underflow. Is there a harness out there that I could just 
adapt to my own needs. Surely that's how other developers do it. If not, 
how *do* you fix bugs?

I've already added some features to JNumeric, and introduced a unit-test 
suite there. I have so few problems using Numeric, I'd really like to nail 
this one involving exp(), since it's holding me back.


-Frank Gibbons

PhD, Computational Biologist,

Harvard Medical School BCMP/SGM-322, 250 Longwood Ave, Boston MA 02115, USA.
Tel: 617-432-3555       Fax: 
617-432-3557       http://llama.med.harvard.edu/~fgibbons

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