<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html
  SYSTEM "about:legacy-compat">
<html xmlns:mml = "http://www.w3.org/1998/Math/MathML" lang = "en"><head><meta charset = "UTF-8"/><meta name = "copyright" content = "(C) Copyright 2020"/><meta name = "DC.rights.owner" content = "(C) Copyright 2020"/><meta name = "DC.type" content = "task"/><meta name = "abstract" content = "Generally, the number of optimization cycles should be limited per default to a certain number to limit the computation time for optimizations with convergence problems."/><meta name = "description" content = "Generally, the number of optimization cycles should be limited per default to a certain number to limit the computation time for optimizations with convergence problems."/><meta name = "DC.format" content = "HTML5"/><meta name = "DC.identifier" content = "tso-t-usr-shape-stop-Glob"/><meta name = "DC.language" content = "en"/><link rel = "stylesheet" type = "text/css" href = "../DSDocUI_XML34.css"/><title>Global Stop Condition (Number of Iterations)</title>
<script type = "text/javascript" src = "../DSDocUI_Highlight34.js">
  	/* */
  	</script></head><body onLoad = "highlightSearchTerms();" id = "tso-t-usr-shape-stop-Glob">
<a name = "hj-top"> </a><table class = "table1" id = "table11"><tr><td><table class = "DocHeader"><tr><td class = "DocHeader1" colspan = "2"><h1>Global Stop Condition (Number of Iterations)</h1></td></tr><tr><td class = "DocHeader4" colspan = "2"/></tr><tr><td class = "DocHeader3" colspan = "2"><table class = "DocThemeIntro" id = "table12"><tr><td class = "Intro1Only"><p class = "header"><p class = "abstract">
<span class = "shortdesc">Generally, the number of optimization cycles should be limited per default to a certain
      number to limit the computation time for optimizations with convergence problems. </span>

</p>

</p></td></tr></table></td></tr></table>



<div class = "body taskbody">
 <p class = "result">
<p>
  The stop criterion is the maximum number of optimization iterations, which is default 50
  for both sensitivity-based and controller-based optimizations. When the maximum
  number of optimization iterations is reached, the optimization algorithm always stops
  independent of other criteria. The allowed maximum number of optimization iterations
  can be increased or decreased by the user. This is defined by the parameter <code class = "ph codeph">ITER_MAX</code> of the <code class = "ph codeph">STOP</code>
  command.
</p>
<pre class = "codeblock">
<code class = "ph codeph">
STOP
 ID_NAME  = global_stop
 ITER_MAX = 5
END_
</code>
</pre>
<p>where <code class = "ph codeph">ITER_MAX</code> is decreased to 5.</p>
<p>A global stop condition is essential to limit the number of design cycles in case no convergence
        is obtained. User-defined stop conditions adapted to the task (instead of using the default
        values) might improve efficiency.</p>
<p>Since a "partially optimized model" can be used as a starting model for a subsequent
        optimization, it makes sense to calculate first a few design cycles and then to use
        information from the optimization result to calculate more design cycles with adjusted
        settings.</p>

<table class = "Remark" id = "table132"><tr><td class = "Remark"><span class = "run-in.important">Important:
				</span><span class = "notecontent">
<ul class = "ul" id = "tso-t-usr-shape-stop-Glob__ul_996E3F2A50D048CDB08CF7AAA098F7F4">
<li class = "li"> For simple shape optimization tasks, it is often
      sufficient to limit the number of iterations to 5 or 10. For more complex setups, the
      iterations should be increased to around 25, which is enough for many cases. However, there
      are setups where even more iterations are needed and it is hard to guess a number that is
      valid for all cases.</li>
<li class = "li"> The global stop criterion leads to a stop of the
      optimization, independent of a complete convergence of the result. For shape optimization
      tasks this is no drawback as the optimization task can be continued for some more steps using
      the input file of the last iteration as start file.</li>
</ul>
</span></td></tr></table>

</p>
</div>

</td></tr></table><script type = "text/javascript" src = "../DSDocUI_Bottom34.js">/* */</script></body>
</html>
