[Numpy-discussion] Floating Point Difference between numpy and numarray

Hanni Ali hanni.ali@gmail....
Wed Sep 3 05:44:42 CDT 2008


Understood, but I would generally be more concerned with accuracy than
memory?


2008/9/3 Matthieu Brucher <matthieu.brucher@gmail.com>

> It should never do some black magic without telling you.
> People are concerned by memory consumption, so if you use more memory
> than what you think, you can encounter bugs. Least surprise is always
> better ;)
>
> Matthieu
>
> 2008/9/3, Hanni Ali <hanni.ali@gmail.com>:
> > Sebastian you legend, that seems to be it.
> >
> > Thank you very much.
> >
> > >>> matrix.mean(dtype='float64')
> > 0.41582015156745911
> >
> > What seems odd is that numpy doesn't do this on it's own...
> >
> >
> >
> > 2008/9/3 Sebastian Stephan Berg <sebastian@sipsolutions.net>
> >
> > > Hi,
> > >
> > > just guessing here. But numarray seems to calculate the result in a
> > > bigger dataype, while numpy uses float32 which is the input arrays size
> > > (at least I thought so, trying it confused me right now ...). In any
> > > case, maybe the difference will be gone if you
> > > use .mean(dtype='float64') (or whatever dtype numarray actually uses,
> > > which seems to be "numarray.MaximumType(a.type())" where
> > a is the array
> > > to take the mean).
> > >
> > > Sebastian
> > >
> > >
> > >
> > >
> > > _______________________________________________
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> > >
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> > >
> >
> >
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> >
>
>
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