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MathGroup Archive 1995

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Re: intransigent root expressions

  • To: mathgroup at christensen.cybernetics.net
  • Subject: [mg633] Re: [mg616] intransigent root expressions
  • From: Count Dracula <lk3a at kelvin.seas.virginia.edu>
  • Date: Mon, 3 Apr 1995 11:03:08 -0400

(Martin McClain) wmm at chem.wayne.edu wites:

>  xExpr = 5.54977*10^-25 * Sqrt[-7.57576*10^47 + 2.16450*10^48*y]

> This would be your answer, if only you could force that tiny exterior
> coefficient to multiply into the huge numbers under the square root.

> Does anybody know a graceful way to do this?  

> My current solution

> x -> Sqrt[xExpr /. m_ Sqrt[n_]->m^2 n // Expand]

Slightly simpler is:

In[2]:= xExpr = 5.54977*10^-25 * Sqrt[-7.57576*10^47 + 2.16450*10^48*y];

In[3]:= xExpr /. Sqrt[x_] :> Sqrt[Factor[x]]

Out[3]= 0.816495 Sqrt[-0.35 + 1. y]

 ___________________________________________________________________________________
 Levent Kitis           lk3a at cars.mech.virginia.edu    lk3a at kelvin.seas.virginia.edu
 University of Virginia  Department of Mechanical, Aerospace and Nuclear Engineering  
 ___________________________________________________________________________________



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