Re: system of nonlinear differential equations
- To: mathgroup at smc.vnet.net
- Subject: [mg48648] Re: system of nonlinear differential equations
- From: V.Cejka at seznam.cz (Vasek)
- Date: Wed, 9 Jun 2004 04:17:13 -0400 (EDT)
- References: <90v42m$6se@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Boundary nonlinear problems can be solved by combination of FindRoot and NDSolve commands. NDSolve must have exact numerical initial conditions, but these conditions can be parameters substituted by FindRoot iteration. Condition of FindRoot command is another boundary condition evaluated from the result of NDSolve function. Actually, syntax in mathematica is not easy and is different in version 4.x and 5.0. See: http://library.wolfram.com/infocenter/MathSource/652/ In Mathematica 5.0 replace y[n_][m_][IBguess_] := First[(y[n][r] /. Evaluate[sol[IBguess]]) /. r->m] FindRoot[ (bign/2*y[1][1][IBguess] + y[2][1][IBguess] - bign/2 == 0), {IBguess, {1.5,1.3}}] with y[n_][m_][IBguess_?NumericQ] := First[(y[n][r] /. Evaluate[sol[IBguess]]) /. r->m] FindRoot[ (bign/2*y[1][1][IBguess] + y[2][1][IBguess] - bign/2 == 0), {IBguess, 1.5,1.3}] On 10 Dec 2000 00:24:38 -0500, Bogdan Wasiluk wrote: > >How could I find solution of the system of nonlinear differential equations? >I can not solve them using DSolve or NDSolve, please see attached file. >I know that boundary conditions for DSolve should be at the same point. > >Best regards, > >Bogdan > >E-mail: bwasiluk at force.energy.kyoto-u.ac.jp