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MathGroup Archive 1992

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FindRoot

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: FindRoot
  • From: deutsch at bu-pub.bu.edu
  • Date: Wed, 9 Sep 92 11:15:09 -0400

Hello,

      I provide Mathematica support for users here at Boston
University. Recently a user has shown me a problem with FindRoot.

Using Timing[s]  where

s := N[ FindRoot[{d1v==0,d2v==0},{p2,p20},{m3,m30}] ,15]

and  d1v := a function of p2 and m3
     d2v := a function of p2 and m3


we observed that the time for solution was about 33 seconds which was
reasonable given the complexity of d1v and d2v. However, when we
repeated the same calculation we observed that the time more than
doubled. Further attempts showed that the time continued to increase
by a factor of 2. Are there any known problems with FindRoot that people
are aware of? Does anyone have any suggestions as to what could be
causing a problem of this type.
   

Thank you,

David Deutsch
Information Technology
Boston University
deutsch at bu-it.bu.edu





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