Re: Non Commutative Multiply
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- Subject: [mg128606] Re: Non Commutative Multiply
- From: mstankus at gmail.com
- Date: Thu, 8 Nov 2012 19:01:30 -0500 (EST)
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On Wednesday, November 7, 2012 11:16:35 PM UTC-8, digo wrote:
> Dear group,
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> I want to multiply two matrices, for example,
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> A = {{e, f}, {g, h}}
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> B = {{a, b}, {c, d}}
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> Using A.B, Mathematica returns
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> {{a e + b g, a f + b h}, {c e + d g, c f + d h}}
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> I would like to get, however, the following result:
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> {{e a + f c, e b + f d}, {g a + h c, g b + h d}}
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> since, for me, the entries {a,b,c,d,e,f,g,h} are operators, i.e., they
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> are non-commutative.
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> I could solve this problem clearing the attribute "Orderless" in the
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> built-in function Times:
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> ClearAttributes[Times, Orderless]
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> I know, however, this can be dangerous. I tried to define a function
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> Times2[a_,b_]:=Times[a,b]
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> and then use ClearAttributes[Times2, Orderless] but it doesn't work.
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> How could I solve this problem?
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> Thanks in advance
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> Rodrigo
You can use NCAlgebrq. See http://www.math.ucsd.edu/~ncalg/
Mark Stankus