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From: Melanie Roberts on 31 Mar 2010 21:48
Hopefully this is an easy question, but I'm wanting to initialise my bvp4c solver using the output of a different solver, consequently I have a vector rather than an equation I'd like to use with bvpinit - how am I to do this?

I've tried with a basic problem but find that if I simply input the vector I end up with my vector repeated as column vectors, so get a 10 x 10 rather than 1 x 10 array.

E.g. if
xint = linspace(0,5,10) and val = xint.^2
and I form
solinit = bvpinit(xint,val)
then
solinit.y(:,0)
returns
0
0.3086
1.2346
2.7778
4.9383
7.7160
11.1111
15.1235
19.7531
25.0000
when I want it to be returning only the 0. Likewise solinit.y(:,5) returns the above rather than just 4.9383.

Any ideas how to get this working would be much appreciated - Melanie
From: Ivan Werning on 31 Mar 2010 23:10
"Melanie Roberts" <kthelephant(a)hotmail.com> wrote in message <hp0u0k$kuf$1(a)fred.mathworks.com>...
> Hopefully this is an easy question, but I'm wanting to initialise my bvp4c solver using the output of a different solver, consequently I have a vector rather than an equation I'd like to use with bvpinit - how am I to do this?
>
> I've tried with a basic problem but find that if I simply input the vector I end up with my vector repeated as column vectors, so get a 10 x 10 rather than 1 x 10 array.
>
> E.g. if
> xint = linspace(0,5,10) and val = xint.^2
> and I form
> solinit = bvpinit(xint,val)
> then
> solinit.y(:,0)
> returns
> 0
> 0.3086
> 1.2346
> 2.7778
> 4.9383
> 7.7160
> 11.1111
> 15.1235
> 19.7531
> 25.0000
> when I want it to be returning only the 0. Likewise solinit.y(:,5) returns the above rather than just 4.9383.
>
> Any ideas how to get this working would be much appreciated - Melanie

What worked for me is to take the solution from another ODE solver (that's what I interpret you want in your first paragraph), say ode45, and use it defined as a structure, i.e.
solinit = ode45(@myfun,...)
and then feed this structure as the guess. Thus, you do not pass the initial solution as a vector, or constructing a guess from a vector (using bvpinit).

Hope this helps.

-Ivan
From: Melanie Roberts on 5 Apr 2010 20:23
Hi Ivan,

Thanks for your reply. Unfortunately that doesn't appear to be working - I think because the previous solution structure involves parameters, while the current problem does not.

Melanie
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