Hi,
Le 02/09/2021 à 20:11, Jakub Kopac a écrit :
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.
The actual generic solvers of ode
(https://computing.llnl.gov/projects/odepack) are still competitive but
for large-scale stiff systems, odepack misses the versatileness of
Sundials concerning linear solvers (e.g. odepack does not handle sparse
Jacobians).
S.
št 2. 9. 2021 o 18:32 Stéphane Mottelet <stephane.motte...@utc.fr
<mailto:stephane.motte...@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)344234688
http://www.utc.fr/~mottelet <http://www.utc.fr/~mottelet>
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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)344234688
http://www.utc.fr/~mottelet
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