[Numpy-discussion] numarray bug: dot product between 2x2 and 3x2x3 on Mac different from PC

Sebastian Haase haase at msg.ucsf.edu
Mon Jul 17 14:26:33 CDT 2006


On Monday 17 July 2006 12:10, Travis Oliphant wrote:
> Sebastian Haase wrote:
> > Traceback (most recent call last):
> >   File "<input>", line 1, in ?
> > TypeError: array cannot be safely cast to required type
> >
> >>>> dd=d.astype(N.float32)
> >>>> N.dot(dd,ccc)
> >
> > [[[ 1.  1.  1.]
> >   [ 1.  1.  1.]
> >   [ 1.  1.  1.]]
> >
> >  [[ 2.  2.  2.]
> >   [ 2.  2.  2.]
> >   [ 2.  2.  2.]]]
> >
> >
> >
> > The TypeError looks like a numpy bug !
>
> I don't see why this is a bug.  You are trying to coerce a 32-bit
> integer to a 32-bit float.  That is going to lose precision and so you
> get the error indicated.
>
> -Travis
In numarray I do not get an error. Would the error go away if I had 64 bit 
float !?  It seems though that  having  ones and twos in an int array should 
fit just fine into a float32 array !?

- Sebastian Haase




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