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## Re: DDE solvers / How to set HISTORY

 From: Sergei Steshenko Subject: Re: DDE solvers / How to set HISTORY Date: Sun, 20 Jan 2019 03:09:04 +0000 (UTC)

On Sunday, January 20, 2019, 12:23:09 AM GMT+2, Maurizio De Pittà <address@hidden> wrote:

Hi Sergei,
unfortunately not. There is no specification of HISTORY as matrix in the MATLAB equivalent:

This is why the matrix specification is hard to figure out, for me at least.

M

On Sat, Jan 19, 2019 at 10:58 PM Sergei Steshenko <address@hidden> wrote:

On Saturday, January 19, 2019, 11:32:28 PM GMT+2, Maurizio De Pittà <address@hidden> wrote:

Dear all,
I am troubled by the DDE solvers in octave. My question follows this question that sadly remained without answer:

In particular, I cannot understand what is the "matrix" that I need to provide as HISTORY in the input argument of any of the octave/dde-solvers -- i.e. any of the odeXXd solvers in the odepkg. There is no explanation on the specifics of this matrix and why it seems to be required to be of size n_var * n_delay. This is very different from MATLAB implementations. Any insight would be helpful.

Maurizio

==================================

I don't have an answer, but maybe Matlab documentation is more clear on the issue. I haven't read either documentation on the issue.

--Sergei.

Well, in GNU Octave: Matlab-compatible solvers I read among other things:

"
: [t, y] = ode23 (fun, trange, init)

...
init contains the initial value for the unknowns. If it is a row vector then the solution y will be a matrix in which each column is the solution for the corresponding initial value in init.
".

My guess is that to resume the solution process form where you've stopped you need to specify 'init' as column (not row) vector.

Take a simple equation and try this.

--Sergei.

"
"

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