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Urgent!! Help about NDSolve

  • To: mathgroup at
  • Subject: [mg28685] Urgent!! Help about NDSolve
  • From: "Diego Martin Martin" <diego at>
  • Date: Wed, 9 May 2001 04:20:06 -0400 (EDT)
  • Sender: owner-wri-mathgroup at


I work on semiconductor manufacturing. Now Im trying to simulate the
behaviour of a p-n juntion (with some particular changes) in a semiconductor
with Mathematica 4.0.

I have a problem when I try to solve the Continuity Equation for minoritary
electrons in the p-type region. This is a Linear with Non-Constant
Coefficients Ordinary Differential Equation with boundary conditions
involving both the function and its derivatives at the start and end of the
integration interval.

When I try to solve it usind NDSolve, I obtain a numerical solution that is
not correct.

Is there some other function or package to solve non-linear differential

Could I obtain some improvement doing the traslation to a system of diff.

Sometimes I obtain an error message that sais I must increase the
WorkingPrecision option, because when trying to evaluate some expresion the
limit was reached. I have tryed to change the AccuracyGoal, PrecisionGoal
and WorkingPrecision options, but the numerical solution remain incorrect.
What can I do to solve this problem?

Thank you in advance. Regards,


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