       Re: FindRoot in Version 5: corrected code

• To: mathgroup at smc.vnet.net
• Subject: [mg46299] Re: FindRoot in Version 5: corrected code
• From: bghiggins at ucdavis.edu (Brian Higgins)
• Date: Fri, 13 Feb 2004 21:57:09 -0500 (EST)
• References: <c0fh4j\$9ls\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi, Opps , the code I posted got warped when I copied it from the
notebook. The "?" should have been a omega. The correct code is given
below

system[w_] := {y1'[x] == y2[
x], y2'[x] == -Sin[y2[x]] + Cos[5x], y1[-1] == 0, y2[-1] == w};
myODEsoln[w_] := NDSolve[system[w], {y1[x], y2[x]}, {x, -1, 1}]
yend[w_] := (y1[x] /. myODEsoln[w]) /. x -> 1
bc = FindRoot[First[yend[w]] == 0, {w, -2, 2}];
Plot[Evaluate[y1[x] /. myODEsoln[w /. bc]], { x, -1, 1}, AxesLabel ->
{"x", "y1(x)"}];

Sorry for the confusion

Brian

bghiggins at ucdavis.edu (Brian Higgins) wrote in message news:<c0fh4j\$9ls\$1 at smc.vnet.net>...
> Hi,
>
> In version 4 I used the following code to solve nonlinear BVP using
> NDSolve
>
> system[?_] := {y1'[x] == y2[
>     x], y2'[x] == -Sin[y2[x]] + Cos[5x], y1[-1] == 0, y2[-1] == ?};
> myODEsoln[?_] := NDSolve[system[?], {y1[x], y2[x]}, {x, -1, 1}]
> yend[?_] := (y1[x] /. myODEsoln[?]) /. x -> 1
> bc = FindRoot[First[yend[?]] == 0, {?, -2, 2}];
> Plot[Evaluate[y1[x] /. myODEsoln[? /. bc]], {
>       x, -1, 1}, AxesLabel -> {"x", "y1(x)"}];
>
> In Version 5 is does not work. I have read on this group that FindRoot
> was modified so that it now requires that in the above code I replace
> yend[Q_] with yend[Q_?NumericQ]. But now the problem is that FindRoot
> fails to converge.
>
> So my question: Does anyone know what other modifications have been
> made to FindRoot so that I can get this code and many others like it
> to work again?
>
> Thanks much
>
> Brian

```

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