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NDSolve Errors: icfail and ntdv

• To: mathgroup at smc.vnet.net
• Subject: [mg77226] NDSolve Errors: icfail and ntdv
• From: ehicks <ehicks at uchicago.edu>
• Date: Wed, 6 Jun 2007 06:43:37 -0400 (EDT)

Hi,
   I am trying to solve a set of equations with NDSolve.  The problem
is no matter what I do, I keep getting errors of various kinds.  I've
used NDSolve successfully in the past, so I am starting to wonder if
maybe this set of equations just doesn't have a solution.   My set is
diffeo-alegbraic, so at first I got the NDSolve::icfail error.  I
tried to circumvent that by taking the derivative of one of the
equations.  Then I got the NDSolve::ntdv error.  So I tried
SolveDelayed->True, which just got me right back to the icfail error.
Does anyone have any ideas on ways to circumvent these errors?
Thanks!
-Elizabeth

See the Mathematica File at: http://www.tarzia.selfip.com/~elizabeth/fullplumemodel1.nb

The text of the errors is:
NDSolve::icfail: Unable to find initial conditions which satisfy the
residual function within specified tolerances.  Try giving initial
conditions for both values and derivatives of the functions.

NDSolve::ntdv: Cannot solve to find an explicit formula for the
derivatives.  Consider using the option setting SolveDelayed->True.