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MathGroup Archive 1996

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Re: Are two expressions equal?

  • To: mathgroup at
  • Subject: [mg5095] Re: [mg5058] Are two expressions equal?
  • From: Allan Hayes <hay at>
  • Date: Wed, 30 Oct 1996 22:03:43 -0500
  • Sender: owner-wri-mathgroup at

jeremy_gorman at (Jeremy Gorman)
>Subject: [mg5058] Are two expressions equal?

>How can I check to see if these expressions are equal?


Instead of looking at q1 == q2 you might try to try and reduce q1 -  
q2 say by

Simplify[q1-q2] or
Expand[q1-q2, Trig -> True]  (*Trig->True for Trig functions*)
Together[q1-q2, Trig -> True]

and combinations of these.

If you get 0 you have proved equality.
If you can find numerical values for the variables and constants  
that definitely give a non-zero value then you will have proved  
inequality. And if a range of random assignments of numerical values  
all give 0 for q1-q2 it is probable that q1=q2.

Allan Hayes
hay at

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