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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>
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    <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>
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          <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>
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                data-smartmail="gmail_signature"><br>
                Best regards</div>
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                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>
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    <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 class="gmail_quote">
          <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>
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              <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>
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              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>
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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-quote-pre" wrap="">_______________________________________________
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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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