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<p>Hi,<br>
</p>
<div class="moz-cite-prefix">Le 02/09/2021 à 20:11, Jakub Kopac a
écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CAPenAnD_DYtz=OFSVdKBOk5n46dXSesuJa1UNArSrYHCbYa+PA@mail.gmail.com">
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<div>Hello,</div>
<div><br>
</div>
<div>In the past I solved the same issue.</div>
<div>As Stephane points out, try to play with ODEOPTIONS.</div>
<div>In my case (disretized PDE), I get massive speed up by
setting
<pre style="font-family:Monospaced;font-style:normal"><span style="color:rgb(0,0,0)">%ODEOPTIONS</span><span style="color:rgb(74,85,219)">(</span><span style="color:rgb(188,143,143)">6</span><span style="color:rgb(74,85,219)">)</span> <span style="color:rgb(92,92,92)">=</span> <span style="color:rgb(188,143,143)">0</span></pre>
</div>
<div>
<div>
<div class="gmail_signature"
data-smartmail="gmail_signature">and selecting a stiff
solver.</div>
<div class="gmail_signature"
data-smartmail="gmail_signature"><br>
</div>
<div class="gmail_signature"
data-smartmail="gmail_signature">If I understand it
correctly, you are using function interp1 when
evaluating ODE function (many calls to interp1).<br>
</div>
<div class="gmail_signature"
data-smartmail="gmail_signature">If it is this case, I
propose to make a copy of Scilab interp1 function and
clean unecessary commands.</div>
<div class="gmail_signature"
data-smartmail="gmail_signature">I have also good
experience with this aproach, but you are loosing
flexibility and is a ad hoc function.<br>
</div>
<div dir="ltr" class="gmail_signature"
data-smartmail="gmail_signature"><br>
Best regards</div>
<div dir="ltr" class="gmail_signature"
data-smartmail="gmail_signature"><br>
</div>
<div class="gmail_signature"
data-smartmail="gmail_signature">J.K.</div>
<div class="gmail_signature"
data-smartmail="gmail_signature"><br>
</div>
<div class="gmail_signature"
data-smartmail="gmail_signature">PS: it is great to hear
that ODE solvers will be updated to more recent
versions.<br>
</div>
</div>
</div>
</div>
</div>
</blockquote>
<p>The actual generic solvers of ode
(<a class="moz-txt-link-freetext" href="https://computing.llnl.gov/projects/odepack">https://computing.llnl.gov/projects/odepack</a>) 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).<br>
</p>
<p>S.<br>
</p>
<blockquote type="cite"
cite="mid:CAPenAnD_DYtz=OFSVdKBOk5n46dXSesuJa1UNArSrYHCbYa+PA@mail.gmail.com">
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<div><br>
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<br>
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<div dir="ltr" class="gmail_attr">št 2. 9. 2021 o 18:32
Stéphane Mottelet <<a
href="mailto:stephane.mottelet@utc.fr"
moz-do-not-send="true">stephane.mottelet@utc.fr</a>>
napísal(a):<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div>
<p><br>
</p>
<div>Le 02/09/2021 à 18:03, CHEZE David 227480 a écrit :<br>
</div>
<blockquote type="cite">
<div>
<p class="MsoNormal">Dear all,</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span lang="EN-GB">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. </span></p>
<p class="MsoNormal"><span lang="EN-GB">WIN10-64bits
Intel i7 2,6GHz, Scilab 6.1.1</span></p>
<p class="MsoNormal"><span lang="EN-GB">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 ?</span></p>
</div>
</blockquote>
No. Xcos uses the (more up-to-date) SUNDIALS solvers, they
will be made available at the user level in the next
months.
<blockquote type="cite">
<div>
<p class="MsoNormal"><span lang="EN-GB"></span></p>
<p class="MsoNormal"><span lang="EN-GB">Thank you for
advising,</span></p>
<p class="MsoNormal"><span
style="font-size:10pt;font-family:"Arial",sans-serif"
lang="EN-GB"> </span></p>
<p class="MsoNormal"><span
style="font-size:10pt;font-family:"Arial",sans-serif">David
</span><span></span></p>
<p class="MsoNormal"> </p>
</div>
<br>
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<pre cols="72">--
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
<a href="http://www.utc.fr/~mottelet" target="_blank" moz-do-not-send="true">http://www.utc.fr/~mottelet</a>
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<pre class="moz-signature" cols="72">--
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
<a class="moz-txt-link-freetext" href="http://www.utc.fr/~mottelet">http://www.utc.fr/~mottelet</a>
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