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Re: Simplifying Sqrt[a^2*d^2] -> a*d

  • To: mathgroup at smc.vnet.net
  • Subject: [mg8395] Re: Simplifying Sqrt[a^2*d^2] -> a*d
  • From: vvs124 at rsphy1.anu.edu.au (Victoria Steblina)
  • Date: Tue, 26 Aug 1997 20:41:35 -0400
  • Organization: Australian National University
  • Sender: owner-wri-mathgroup at wolfram.com

In article <5tjftc$drn at smc.vnet.net>
carlos at mars.Colorado.EDU (Carlos A. Felippa) writes:

> I want Sqrt[a^2*d^2] to be automatically simplified to a*d
> wherever it appears in a very complex expression.  
> 
> In another system I simply declare a and d real nonnegative and let the
> program figure out the rest.  How do I do that in Mathematica?  
> The obvious rule expr/.{Sqrt[a^2*d^2]->a*d}  does not work.
> 
> 

You can do it this way:

(local) In[1]:=  Unprotect[Sqrt];
                 Sqrt[a^2*d^2] = a*d;
                 Protect[Sqrt];

(local) In[4]:=  Sqrt[a^2*d^2] + Sqrt[a^2*d^2]^3

                         3  3
(local) Out[4]=   a d + a  d    


Cheers,
Victoria


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