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MathGroup Archive 1997

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Mathematica Technical Question

  • To: mathgroup at
  • Subject: [mg7234] Mathematica Technical Question
  • From: "Mark T. Lusk" <mlusk at druid.Mines.EDU>
  • Date: Sat, 17 May 1997 19:13:25 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

First of all, thanks for setting up and supporting the Mathematica User Group.
 I have just discovered it.

I am trying to use NDSolve to evaluate solutions to fourth order reaction
diffusion equations (one time derivative, four spatial derivatives, nonlinear
in either the dependent variable or its derivative).  I have used this routine
successfully on second order, nonlinear pde's and have tried just about
everything to get the call to solve such Cahn-Hilliard type equations.  I get
all sorts of error remarks about starting step size and singularities.  These
are typically concluded with "Internal error: FreeExpr called on live expr".  I
don't even know what this means.  Certainly there must be some folks out there
who have used Mathematica to solve such equations succesfully.

Any help would be greatly appreciated.  Thanks very much.

Mark T. Lusk

Division of Engineering, Colorado School of Mines
1500 Illinois Street, Golden, CO  80401
303-273-3675 (voice), 303-273-3602 (FAX)

mlusk at

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