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Re: Mathematica question about commutativity of multiplication

  • To: mathgroup at smc.vnet.net
  • Subject: [mg96741] Re: Mathematica question about commutativity of multiplication
  • From: Scott Hemphill <hemphill at hemphills.net>
  • Date: Mon, 23 Feb 2009 05:03:29 -0500 (EST)
  • References: <gnq6u3$89g$1@smc.vnet.net>
  • Reply-to: hemphill at alumni.caltech.edu

James <james545 at gmail.com> writes:

> Dear users,
>
> I have a 6x6 matrix in terms of 
> 3 variables a,b,c.  That is, each entry in the matrix
> is some polynomial in the variables a,b,c 
> with integer coefficients.
>
> I wish to calculate the eigenvalues of this matrix, so
> if the matrix is called A, I type in Eigenvalues[A].
>
> The problem is that the output is 500 pages long, so is
> not useful to me.  I think part of the issue is that 
> in my case, the variables a,b, and c commute.  That is,
> ab = ba, ac = ca, and bc = cb.  I really believe that
> if I could tell Mathematica that multiplication commutes
> with my variables, then the output would be simpler.

If "a" is a variable and "b" is a variable, their product is "a*b" or
"a b".  "ab" is just another variable unrelated to "a" and "b".

Scott
-- 
Scott Hemphill	hemphill at alumni.caltech.edu
"This isn't flying.  This is falling, with style."  -- Buzz Lightyear


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