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Re: Replacement


In article <4shud7$g7n at ralph.vnet.net>,
   ges at vsnhdd.cern.ch (Sergej Gerassimov) wrote:
->Hi,
->
->I have something like 
->
->x/Sqrt[a^2+b^2]+Sqrt[a^2+b^2]/y 
->
->and I'd like to substitute Sqrt[a^2+b^2] by r.
->
->x/Sqrt[a^2+b^2]+Sqrt[a^2+b^2]/y //. Sqrt[a^2+b^2]->r
->gives:
->
->      x         r
->------------- + -
->Sqrt[a^2+b^2]   y
->
->(replace one only in the numerator)
->How to replace Sqrt[a^2+b^2] by r everywhere in the expression?
->
->Thanks.
->				S.

In[]:=  x/Sqrt[a^2+b^2]+Sqrt[a^2+b^2]/y //. 
        (a^2+b^2)^Rational[ n_, 2 ] -> r^n
Out[]=  x   r
        - + -
        r   y

Paul

**************************************************************************
* Paul A. Rubin                                  Phone: (517) 432-3509   *
* Department of Management                       Fax:   (517) 432-1111   *
* Eli Broad Graduate School of Management        Net:   RUBIN at MSU.EDU    *
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they translate it into their own language, and at once it is something
entirely different.                                    J. W. v. GOETHE

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