[Numpy-discussion] NA.dot transposing in place

Todd Miller jmiller at stsci.edu
Thu Jul 15 07:38:00 CDT 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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