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Re: overloading times operator

  • To: mathgroup at smc.vnet.net
  • Subject: [mg88830] Re: overloading times operator
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Sat, 17 May 2008 23:29:12 -0400 (EDT)
  • References: <g0m918$3n$1@smc.vnet.net>

Hi,

it's frustrating to repeat, that we can only answer a question when
we get the full code and *not* a mixture of Mathematica and TeX
and not a description like

"wrote a procedure to define the non-commutative product"

because the problem is probably in that "procedure to define the 
non-commutative product" and we can't help you if you don't
write how this "procedure to define the non-commutative product"
is defined.

Regards
   Jens

gstaples wrote:
> I wrote a procedure to define the non-commutative product of two elements of the form e_X e_Y, where X and Y are multi-indices.  I do this using Times.
> 
> I do a simple calculation like
>  
> Expand[(e_{1} + e_{3})(e_{1} - e_{3})]
> 
> and get the wrong answer.  (On the first try.)
> 
> If I then re-execute the code that defines the multiplication, I repeat the calculation and get correct output.
> 
> Alternatively, if I execute
> 
> e=Symbol["e"] 
> 
> before loading the procedure, I get correct output on the first try.  
> 
> More troubling is that after getting correct output, if I perform calculations of a different kind (e.g. matrix multiplication), when I repeat my original calculation, I start getting incorrect output again.  (Until I re-execute the code that defines the multiplication.)
> 
> It's frustrating to repeat a calculation and get different sets of output depending on what other calculations are done in between.
> 
> Does anyone have suggestions?
> 


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