On Mar 8, 2009, at 11:43 , alex wrote:
>
> How can i compute the matrix multiplication (product) of two symbolic
> matrices in sage ?
I'm not an expert in this part of Sage, but I think you need to get
more explicit about what you are doing. Real experts can correct me
where I err.
In Sage, there is a "symbolic ring" that supports all symbolic
computation. When you declare variables:
sage: var('x y z w')
(x, y, z, w)
these elements belong to that ring:
sage: x.parent()
Symbolic Ring
The name of the ring is 'SR':
sage: SR
Symbolic Ring
This seems to give you what you want:
sage: M = Matrix(SR,2,2,[x,y,z,w])
sage: M
[x y]
[z w]
sage: M*M
[y*z + x^2 x*y + w*y]
[x*z + w*z y*z + w^2]
sage: M^-1
[ w/(w*x - y*z) -y/(w*x - y*z)]
[-z/(w*x - y*z) x/(w*x - y*z)]
HTH,
Justin
--
Justin C. Walker, Curmudgeon at Large
Director
Institute for the Enhancement of the Director's income
-----------
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They said it couldn't be done, but sometimes,
it doesn't work out that way.
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