[Numpy-discussion] NA.dot transposing in place
Curzio Basso
curzio.basso at unibas.ch
Thu Jul 15 07:22:01 EDT 2004
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?
thanks, curzio
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