[Scilab-users] ode, speed issue or tips to speed up ?

[Jakub Kopac]

Hello,

In the past I solved the same issue.
As Stephane points out, try to play with ODEOPTIONS.
In my case (disretized PDE), I get massive speed up by setting

%ODEOPTIONS(6) = 0

and selecting a stiff solver.

If I understand it correctly, you are using function interp1 when
evaluating ODE function (many calls to interp1).
If it is this case, I propose to make a copy of Scilab interp1 function and
clean unecessary commands.
I have also good experience with this aproach, but you are loosing
flexibility and is a ad hoc function.

Best regards

J.K.

PS: it is great to hear that ODE solvers will be updated to more recent
versions.


št 2. 9. 2021 o 18:32 Stéphane Mottelet <stephane.mottelet at utc.fr>
napísal(a):

>
> Le 02/09/2021 à 18:03, CHEZE David 227480 a écrit :
>
> Dear all,
>
>
>
> In experimental work, I’m comparing dynamic model of a thermal system with
> measurements. I’m using function ode, “fix” solver (continuous time, lowest
> accuracy requirement is applying in my case at this stage) and Jacobian (
> to try to speed up the calculation but not sensitive as for now) to get the
> solution of the equation,  a single temperature node, at 240 times (time
> vector), default rtol=1.d-3 and atol=1.d-4. The system inputs are available
> as vector of reals , size is 240 and inputs are passed to the ode function
> as inputs functions by interpolating (interp1) the inputs vectors. It is
> issuing correct temperature solutions but is very slow, ~40s for 240 times,
> while the variable inputs vector are actually not varying a lot and thus I
> would expect very short calculation time.
>
> WIN10-64bits Intel i7 2,6GHz, Scilab 6.1.1
>
> Is there any tips to speed up the calculation , advanced example
> documentation about ODEOPTIONS or ode_optional_output ? I guess it’s the
> same underlying code that is used in Xcos isn’t it ?
>
> No. Xcos uses the (more up-to-date) SUNDIALS solvers, they will be made
> available at the user level in the next months.
>
> Thank you for advising,
>
>
>
> David
>
>
>
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>
> --
> Stéphane Mottelet
> Ingénieur de recherche
> EA 4297 Transformations Intégrées de la Matière Renouvelable
> Département Génie des Procédés Industriels
> Sorbonne Universités - Université de Technologie de Compiègne
> CS 60319, 60203 Compiègne cedex
> Tel : +33(0)344234688http://www.utc.fr/~mottelet
>
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