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How to pass initial conditions to IDA methods via NDSolve?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg121819] How to pass initial conditions to IDA methods via NDSolve?
  • From: GRW <georgwalther at gmail.com>
  • Date: Tue, 4 Oct 2011 01:30:10 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

New to Mathematica so this might be gibberish.

I'm trying to integrate numerically a PDE system. NDSolve complains
saying this:

"NDSolve::icfail: Unable to find initial conditions that satisfy the
residual function within specified tolerances. Try giving initial
conditions for both values and derivatives of the functions."

Now I've figured out how to get numerical estimates for some of the
derivatives in my PDE system (using FindRoot there).
However, if I add these conditions to my preexisting list of initial
conditions and boundary conditions, Mathematica complains that there
are too many boundary and/or initial conditions:

"NDSolve::ivone: Boundary values may only be specified for one
independent variable. Initial values may only be specified at one
value of the other independent variable"

It seems as if IDA was selected automatically as "Method" option of
NDSolve and IDA does not seem to allow for initial conditions passed
to it.

I've tried using Method option "Shooting" (because this one seems to
allow for initial conditions passed), however NDSolve isn't too fond
of that one either:
"NDSolve::nodae: The method NDSolve`Shooting is not currently
implemented to solve differential-algebraic equations. Use Method ->
Automatic instead."


Any advice greatly appreciated!



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