       Re: Boundary conditions in NDSolve

• To: mathgroup at smc.vnet.net
• Subject: [mg56811] Re: [mg56773] Boundary conditions in NDSolve
• From: Chris Chiasson <chris.chiasson at gmail.com>
• Date: Fri, 6 May 2005 03:01:09 -0400 (EDT)
• References: <200505051003.GAA22073@smc.vnet.net>
• Reply-to: Chris Chiasson <chris.chiasson at gmail.com>
• Sender: owner-wri-mathgroup at wolfram.com

```Take a guess at the derivative on the left edge. Comput the function
value at the right edge. Guess a new value and recompute... After your
search is reasonably wide, you could hone down on the lhs derivatives
that give the rhs boundary condition.

I am having a similar problem, but with PDEs and more variables...

On 5/5/05, YZ <z at ***.ohio-state.edu> wrote:
> Hello,
>
> when I NDSolve a 2nd order DE, I cant seem to give two boundary
> conditions at different point of an interval I am solving it on:
>
> NDSolve[{f''[x]==K^2*Sin[f[x]],f'[-L]==A, f[-L]==B},f,{x,-L,L}]
> produces good result, but i.e.
>
> NDSolve[{f''[x]==K^2*Sin[f[x]],f'[-L]==A, f[L]==B},f,{x,-L,L}]
>   ____here derivative is given at left edge, but the functi0n itself is
> given at the right edge___
>
> produces error:
>
> NDSolve::"bvlin"
> "The differential equation(s) and/or boundary conditions are not linear
> in the dependent variables. NDSolve requires linearity to compute the
> solution of a multipoint boundary value problem. "
>
> Is there a way around this?
>
> Thanks
>
> YZ
>
>

--
Chris Chiasson
http://chrischiasson.com/
1 (810) 265-3161

```

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