It appears that matrixmultiply( A,B) has a side-effect of transposing the
second argument (B).
Is this supposed to happen?
Is there anyway to prevent it from transposing?
This shows what happens:
#! /usr/bin/env python
from numarray import *
A=array([[350],
[370],
[510],
[490],
[500]])
B=array([[35,37,51,49,50]])
print "A and B before matmul:"
print A
print B
AB=matrixmultip ly(A,B)
print "AxB, A, B, after matmul:"
print AB
print A
print B
print"Apparantl y, the second argument of matrixmultiply( A,B) is always
transposed."
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On Mon, 19 Jul 2004, Raoul wrote: A=array([[350],
[370],
[510],
[490],
[500]])
B=array([[35,37,51,49,50]])
print "A and B before matmul:"
print A
print B
AB=matrixmultip ly(A,B)
print "AxB, A, B, after matmul:"
print AB
print A
print B
This works for me (B before == B after). Which version of numarray are
you using?
This works for me (B before == B after). Which version of numarray are
you using?
It's version 1.0, on Python 2.3+.
I do have one lengthy example where the second argument was not changed
(on one matmul, all the others in that example did transpose), but was
not able to reproduce that in a small example; so it seems not to be
consistent.
For completeness, here's my output, as you can see the row-vector B has
changed into a column-vector.
A and B before matmul:
[[350]
[370]
[510]
[490]
[500]]
[[35 37 51 49 50]]
AxB, A, B, after matmul:
[[12250 12950 17850 17150 17500]
[12950 13690 18870 18130 18500]
[17850 18870 26010 24990 25500]
[17150 18130 24990 24010 24500]
[17500 18500 25500 24500 25000]]
[[350]
[370]
[510]
[490]
[500]]
[[35]
[37]
[51]
[49]
[50]]
Apparantly, the second argument of matrixmultiply( A,B) is always transposed.
Raoul wrote: It appears that matrixmultiply( A,B) has a side-effect of transposing the
second argument (B).
I can verify this on Mac OSX with the latest CVS of numarray. Please
post a bug report to the tracker. http://sourceforge.net/tracker/?atid...69&func=browse
--
Robert Kern rk***@ucsd.edu
"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter
On Mon, 19 Jul 2004, Raoul Meuldijk wrote: This works for me (B before == B after). Which version of numarray are
you using?
It's version 1.0, on Python 2.3+.
I do have one lengthy example where the second argument was not changed
(on one matmul, all the others in that example did transpose), but was
not able to reproduce that in a small example; so it seems not to be
consistent.
Okay, I was using 0.9. Upgrading to 1.0 confirms the error. This is a
bug in numarray, but it has already been fixed in CVS. As a temporary
fix, use the original Python definition (ripped from numarraycore.py ):
def dot(array1, array2):
return ufunc.innerprod uct(array1, swapaxes(array2 , -1, -2))
matrixmultiply = dot
This will fix both matrixmultiply and dot, as they are both affected by
the bug.
Robert Kern wrote: Raoul wrote:
It appears that matrixmultiply( A,B) has a side-effect of transposing the
second argument (B).
I can verify this on Mac OSX with the latest CVS of numarray. Please
post a bug report to the tracker.
http://sourceforge.net/tracker/?atid...69&func=browse
I have reported it, thanks. Okay, I was using 0.9. Upgrading to 1.0 confirms the error. This is a
bug in numarray, but it has already been fixed in CVS. As a temporary
fix, use the original Python definition (ripped from numarraycore.py ):
def dot(array1, array2):
return ufunc.innerprod uct(array1, swapaxes(array2 , -1, -2))
matrixmultiply = dot
This will fix both matrixmultiply and dot, as they are both affected by
the bug.
Your fix works perfectly! Thanks!
Raoul This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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