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Re: Urgent!! Help about NDSolve

• To: mathgroup at smc.vnet.net
• Subject: [mg28712] Re: Urgent!! Help about NDSolve
• From: "Paul Lutus" <nospam at nosite.com>
• Date: Thu, 10 May 2001 07:54:56 -0400 (EDT)
• References: <9dauml$e1u@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

"Diego Martin Martin" <diego at ies-def.upm.es> wrote in message
news:9dauml$e1u at smc.vnet.net...
> Hello,
>
> 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
> equations?
>
> Could I obtain some improvement doing the traslation to a system of diff.
> equations?
>
> 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?

That should be simple. Tell us what the problem is, your solution, and
specify what is meant by "incorrect" -- what source are you relying on for a
correct solution? Without this essential information, we can only say, "Umm,
there must be some sort of problem."

--
Paul Lutus
www.arachnoid.com