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question

• To: mathgroup at christensen.cybernetics.net
• Subject: [mg1496] question
• From: "Richard Conn Henry" <rch at msx4.pha.jhu.edu>
• Date: Mon, 19 Jun 1995 01:56:12 -0400

Steve, you were kind enough to supply me with information on MathTensor, and I 
have ordered a copy of the book and when I have examined it I may well order 
MathTensor.  Thanks.

I have a question; a general question about Mathematica.  If you can answer it, 
obviously I would appreciate it.  If you don't know the answer, can you give me 
an email address that would result in a useful answer?

Here's the question:  result= a b c d

a,b,c,d are long algebraic expressions, but one of them, d, often is zero.  Even
then, Mathematica grinds away wasting time calculating a,b, and c, quite 
uselessly.  If I switch to    result= d a b c    will that fix it?  Or how?

(I don't just try it because its buried in complex code and involving large 
numbers of such cases; I don't want to change the code unless I am assurred it 
is going to shorten calculations substantially.)

Thanks for any help you can provide.