On Mar 9, 2009, at 4:44 AM, David Joyner wrote:
> On Sun, Mar 8, 2009 at 1:43 PM, alex
> <alessandro.bernardini.1...@gmail.com> wrote:
>>
>> How can i compute the matrix multiplication (product) of two symbolic
>> matrices in sage ?
>>
>> I have tried:
>> A = maxima("matrix ([a, b], [c, d])")
>> AI= A.invert()
>>
>> and
>> A * AI
>> gives
>> matrix([a*d/(a*d-b*c),-b^2/(a*d-b*c)],[-c^2/(a*d-b*c),a*d/(a*d-b*c)])
>
>
> Do you want the following?
>
> sage: a,b,c,d = var("a,b,c,d")
> sage: A = matrix ([[a, b], [c, d]])
> sage: AI = A.inverse()
> sage: P = A*AI; P
>
> [a*d/(a*d - b*c) - b*c/(a*d - b*c) 0]
> [ 0 a*d/(a*d - b*c) - b*c/(a*d - b*c)]
sage: P.simplify_rational()
[1 0]
[0 1]
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