[Numpy-discussion] NA.dot transposing in place
Todd Miller
jmiller at stsci.edu
Thu Jul 15 07:38:00 EDT 2004
On Thu, 2004-07-15 at 10:21, Curzio Basso wrote:
> Hi all.
>
> I wonder if anyone noticed the following behaviour (new in 1.0) of the
> dot/matrixmultiply functions:
>
> >>> alpha = NA.arange(10, shape = (10,1))
>
> >>> beta = NA.arange(10, shape = (10,1))
>
> >>> NA.dot(alpha, alpha)
> array([[285]])
>
> >>> alpha.shape # here it looks like it's doing the transpose in place
> (1, 10)
>
> >>> NA.dot(beta, alpha)
> array([[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
> [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
> [ 0, 2, 4, 6, 8, 10, 12, 14, 16, 18],
> [ 0, 3, 6, 9, 12, 15, 18, 21, 24, 27],
> [ 0, 4, 8, 12, 16, 20, 24, 28, 32, 36],
> [ 0, 5, 10, 15, 20, 25, 30, 35, 40, 45],
> [ 0, 6, 12, 18, 24, 30, 36, 42, 48, 54],
> [ 0, 7, 14, 21, 28, 35, 42, 49, 56, 63],
> [ 0, 8, 16, 24, 32, 40, 48, 56, 64, 72],
> [ 0, 9, 18, 27, 36, 45, 54, 63, 72, 81]])
>
> >>> alpha.shape, beta.shape # but not the second time
> ((1, 10), (10, 1))
>
> -------------------------------------------------
>
> Can someone explain me what's going on?
It's a bug introduced in numarray-1.0. It'll be fixed for 1.1 in a
couple weeks.
Regards,
Todd
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