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Re: trying to "simplify" very large output

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  • Subject: [mg83092] Re: trying to "simplify" very large output
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at>
  • Date: Sat, 10 Nov 2007 03:43:48 -0500 (EST)
  • Organization: The Open University, Milton Keynes, UK
  • References: <fh1btf$an7$>

Basjsmit wrote:

> When I used Mathematica to solve a certain expression, the output was 
> extremely large, somewhere around 10 000 characters. When I looked more 
> closely at the output, I noticed certain frases kept repeating. I havent 
> found anything in the help, but Im wondering if there is a function that can 
> replace those frases with a variable and set that variable once. An example:
> t-> -(y z-v x Cos[k]^2-v x Sin[k]^2)/(z^2-x^2 Cos[k]^2-x^2 Sin[k]^2)-1/2 
> \[Sqrt]((4 (y z-v x Cos[k]^2-v x Sin[k]^2) ........
> becomes:
> A = y z-v x Cos[k]^2-v x Sin[k]^2
> B = z^2-x^2 Cos[k]^2-x^2 Sin[k]^2
> t-> -A / B -1/2 \[Sqrt]((4 A ........
> Thanks in advance, Bas
> PS: just curious, is there a name for the proces I described above? 

Transformation rules and replacement operators are your friends here. 
You should familiarize yourself with the following set of tutorials, 
available in the documentation center


or online at


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