[Numpy-discussion] Using sum() within a function
Jim Cser
jimcser at pacifier.com
Mon Aug 16 09:59:07 CDT 2004
Perry Greenfield wrote:
> Jim Cser wrote:
>
>>Instead, I'm trying to do something like--
>>def f3(x,y,z):
>> for t in range(numT):
>> tempval = f1(x,y,z,t) * f2(y,z,t)
>>
>> outval = sum(tempval,axis = 3)
>> return outval
>>
>
> Perhaps I'm confused but it seems to me the for loop is wrong.
>
> Don't you want something like:
>
> def f3(x,y,z):
> tempval = 0.*x
> for t in range(numT):
> tempval += f1(x,y,z,t) * f2(y,z,t)
> return tempval
>
> Instead?
>
> Not that I've tried this, but so long as the function will
> work given 3-d arrays for x,y,z, it should. (though the dependence
> on numT as a global is a bit worrisome)
>
> Perry GReenfield
The loop was indeed wrong, and "tempval = 0.*x" was the trick I needed,
thanks. Unfortunately, iterating over t is still extremely slow.
Ideally, there would be a way to use fromfunction() with slices as
arguments.
-Jim
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