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Date: Thu, 05 Jun 2003 14:25:09 -0500
From: Wesley Groleau <wesgroleau@despammed.com>
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Subject: Re: Is ther any sense in *= and matrices?
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Date: 2003-06-05T14:25:09-05:00
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>>I mean even if one define "*" for Matrix_Type one cannot do:
>>
>>  A := A * B
> 
> You can, iff A and B are square matrices.

But you cannot do it efficiently "in-place"
because each element in the result is the sum
of multiply operators on several pairs of
elements in the two addends.  So if I compute

A(1,1) before A (1,2) then the latter has already
had one of its inputs changed.  To overcome this
without introducing a temporary "A" one would
require a rather complicated set of temporary
_parts_ of A.