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## Re: [ff3d-users] trivial solution

 From: Mourad Ismail Subject: Re: [ff3d-users] trivial solution Date: Mon, 7 Mar 2005 21:24:30 +0100 User-agent: KMail/1.7.2

```Hi,
I am not sure to have understood, but it seems obvious that you have the
trivial solution.  Your problem doesn't have a unique solution!
The initial guess is 0 which is  a solution of the problem.
Don't hesitate to tell me if I am mistaken.

Best regards,

On Monday 07 March 2005 20:38, Neil Christensen wrote:
> Hi,
>     I am trying solve the pde:
>
>     div(grad(phi))  + phi = 0
>
> with the boundary condition
>
>     phi = 0 on <1,0,0>.
>
> As you know the analytic solution to this is
>
>     phi = sum_i  a_i cos(k_i . r) + b_i sin(k_i . r)
>
> where a_i, b_i and k_i are chosen such that the boundary condition is
> satisfied.  In my first attempt, the boundary I used was a square.  The
> problem is that when I run ff3d on it, I only get the trivial solution
> phi = 0.  How can I get other solutions?
>     Thank you,
> Neil
>
>
> _______________________________________________
> ff3d-users mailing list
> http://lists.nongnu.org/mailman/listinfo/ff3d-users

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```

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