Hi,
I got the following error in a Sage program I wrote:
TypeError: unsupported operand parent(s) for '*': 'Full MatrixSpace of 2 by 1
dense matrices over Integer Ring' and 'Full MatrixSpace of 2 by 2 dense
matrices over Rational Field'
for the following instruction:
--> 152 vA = v.transpose() * invA
Here, v is a vector of dimension n, and invA is a n x n matrix.
In mathematics, a vector of dimension n is usually considered as a n x 1
matrix, thus to multiply it to the left of a n x n matrix, one has first
to transpose it.
sage: m = matrix(SR,[[a,b],[c,d]]); m
[a b]
[c d]
sage: v = vector(SR, [d,e]); v
(d, e)
sage: m * v
(a*d + e*b, c*d + e*d)
sage: v.transpose() * m
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
/users/cacao/zimmerma/.sage/temp/patate.loria.fr/9803/_users_cacao_zimmerma_Adm_Cacao_ANC_Hadamard_algo2_sage_6.py
in <module>()
/usr/local/sage-3.4-core2/sage/local/lib/python2.5/site-packages/sage/structure/element.so
in sage.structure.element.Matrix.__mul__ (sage/structure/element.c:11263)()
/usr/local/sage-3.4-core2/sage/local/lib/python2.5/site-packages/sage/structure/coerce.so
in sage.structure.coerce.CoercionModel_cache_maps.bin_op
(sage/structure/coerce.c:5848)()
TypeError: unsupported operand parent(s) for '*': 'Full MatrixSpace of 2 by 1
dense matrices over Symbolic Ring' and 'Full MatrixSpace of 2 by 2 dense
matrices over Symbolic Ring'
but v * m works:
sage: v * m
(a*d + e*c, b*d + e*d)
I find this rather counter-intuitive wrt mathematics. Is there any rationale?
Paul Zimmermann
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