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Re: overloading times operator

  • To: mathgroup at smc.vnet.net
  • Subject: [mg88825] Re: overloading times operator
  • From: "David Park" <djmpark at comcast.net>
  • Date: Sat, 17 May 2008 23:28:16 -0400 (EDT)
  • References: <g0m918$3n$1@smc.vnet.net>

You didn't show us the procedure.

In any case, it is probably risky to overload Times for this purpose. Why 
not use NonCommutativeMultiply or CircleTimes?

-- 
David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/


"gstaples" <gstaceystaples at yahoo.com> wrote in message 
news:g0m918$3n$1 at smc.vnet.net...
>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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