[SciPy-dev] [SciPy-user] operations on int8 arrays

Charles Harris charles.harris at sdl.usu.edu
Thu Oct 20 12:16:11 CDT 2005


Travis,

> It would be possible to make the default reduce type for integers 32-bit 
> on 32-bit platforms and 64-bit on 64-bit platforms.  the long integer type.
>
> Do people think that would be a good idea?  These kinds of questions do 
> come up.
>

I think it would be best to upcast the type. As others have pointed out, the
unexpected rollover of the sum can cause trouble. Rollover is even more of a
problem with the int8 type being used for booleans. I suppose one could always
typecast the array *before* summing or add a flag to indicate that a higher 
precision should be used. Actually, loss of precision can even be a problem for
large float arrays that should really be accumulated in double precision and then,
so some sort of flag could be useful in any case. Using a larger type is unlikely
to cause space problems as the sum reduces the number of elements in the array. 

Chuck

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