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