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<p class="MsoNormal"><span lang="EN-US">Hi there<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Many of our in-house types as well as the few TESS types that I’ve looked at solve their ODEs internally, using a wide variety of methods from numerical to evaluating the explicit solution directly.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I’m very unclear about the (dis-)advantages of doing that vs. using the TRNSYS built-in functionality of DERIVATIVES/setNumericalDerivative/getNumericalSolution. Is DERIVATIVES & friends just<o:p></o:p></span></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span lang="EN-US">A user-friendly utility that helps a type developer may use to solve their ODEs<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span lang="EN-US">The preferred way of solving ODEs for overall convergence reasons (by “overall” I mean system-wide; between all units)<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span lang="EN-US">…for overall correctness reasons?<o:p></o:p></span></li></ol>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">My question is “informed” by Wikipedia’s page on DAEs:
<a href="https://en.wikipedia.org/wiki/Differential-algebraic_system_of_equations">
https://en.wikipedia.org/wiki/Differential-algebraic_system_of_equations</a>.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">After skimming through it, I was wondering what it means if (for the purpose of this discussion) the ODEs of all units within a simulation are hidden in the blackbox of their corresponding unit, then the system to TRNSYS’
eyes is completely “algebraic”…<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Are we developing are in-house types in a “wrong” way?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Cheers,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Damian<o:p></o:p></span></p>
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