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<p>Dear All,</p>
<p><br>
</p>
<p>I am running the latest release of PDELab on a Mac OX 10.10.5. <span style="font-size: 12pt;">I am implementing a multilevel monte carlo algorithm which is wrapped around a general model (in this case linear elasticity which uses SEQ_CG_AMG_SSOR for the
solver.</span><span style="font-size: 12pt;">)</span></p>
<p><br>
</p>
<p>All works well and is tested in series. <span style="font-size: 12pt;">I have now tried to simply parallelise a for loop which computes a number of independent samples (see below). getSample is a function which returns a quantity of interest from my model
and nproc is the number of processors.</span></p>
<p><br>
</p>
<p>When I do this, all processors with rank from 0 to (nproc -2) return values of NaN. If I run the code on 1 processor all works ok. </p>
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<div>Thanks in advance for your help!</div>
<div><br>
</div>
<div>Tim</div>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo; color: rgb(29, 148, 33);">
<br>
</p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo; min-height: 21px;">
<span style="color: rgb(195, 34, 117);">int</span> numSamples = N[L] / nproc + <span style="color: rgb(4, 53, 255);">
1</span>; <span style="color: rgb(29, 148, 33);">// Compute number of samples on each processor (rounding up)</span></p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo; min-height: 21px;">
<span style="color: rgb(195, 34, 117);"><br>
</span></p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo; min-height: 21px;">
<span style="color: rgb(195, 34, 117);">double</span> * Ytmp = <span style="color: rgb(195, 34, 117);">
new</span> <span style="color: rgb(195, 34, 117);">double</span>[numSamples];<br>
</p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo; min-height: 21px;">
</p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo;">
<span style="font-variant-ligatures: no-common-ligatures; color: #c32275">double</span> * Yroot =
<span style="font-variant-ligatures: no-common-ligatures; color: #c32275">NULL</span>;</p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo; min-height: 21px;">
<span style="color: rgb(195, 34, 117);"><br>
</span></p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo; min-height: 21px;">
<span style="color: rgb(195, 34, 117);">if</span> (rank == <span style="color: rgb(4, 53, 255);">
0</span>){<span> </span>Yroot = <span style="color: rgb(195, 34, 117);">new</span>
<span style="color: rgb(195, 34, 117);">double</span>[numSamples * nproc];<span> </span>}</p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo; min-height: 21px;">
</p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo; min-height: 21px;">
<span style="color: rgb(195, 34, 117);">for</span> (<span style="color: rgb(195, 34, 117);">int</span> i =
<span style="color: rgb(4, 53, 255);">0</span>; i < numSamples; i++){<span> </span>Ytmp[i] = getSample(L,z);<span> </span>}</p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo; min-height: 21px;">
</p>
<p></p>
<p style="margin-right: 0px; margin-left: 0px; font-size: 18px; font-family: Menlo;">
MPI_Gather(Ytmp,numSamples,MPI_DOUBLE,Yroot,numSamples,MPI_DOUBLE,<span style="font-variant-ligatures: no-common-ligatures; color: #0435ff">0</span>,MPI_COMM_WORLD);</p>
<p><br>
</p>
<p><br>
</p>
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<p><span style="font-family:'Courier New',monospace"><strong>Dr Tim Dodwell</strong></span><br>
</p>
<p><span style="font-family:'Courier New',monospace">Lecturer in Engineering Mathematics</span></p>
<p><span style="font-family:'Courier New',monospace">Rm 221 - Harrison Building</span></p>
<p><span style="font-family:'Courier New',monospace">College of Engineering, Mathematics & Physical Sciences</span></p>
<p><span style="font-family:'Courier New',monospace">University of Exeter</span></p>
<p><span style="font-family:'Courier New',monospace">Exeter</span></p>
<p><span style="font-family:'Courier New',monospace">Devon</span></p>
<p><span style="font-family:'Courier New',monospace">EX4 4PY</span></p>
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<p><span style="font-family:'Courier New',monospace"><strong>mail:</strong> t.dodwell(at)exeter.ac.uk</span></p>
<p><span style="font-family:'Courier New',monospace"><strong>tel:</strong> +44 (0)1392 725899</span></p>
<p><span style="font-family:'Courier New',monospace"><strong>mob:</strong> +44 (0)7745 622870</span></p>
<p><span style="font-family:'Courier New',monospace"><span style="font-family:'Courier New',monospace"><strong>web:</strong> </span></span><span style="font-size:12pt; font-family:'Courier New',monospace"><span style="font-family:'Courier New',monospace"><a href="http://emps.exeter.ac.uk/engineering/staff/td336" title="http://emps.exeter.ac.uk/engineering/staff/td336 Cmd+Click or tap to follow the link" tabindex="-1" disabled="true" id="LPNoLP">http://emps.exeter.ac.uk/engineering/staff/td336</a></span></span></p>
<p><span style="font-size:12pt; font-family:'Courier New',monospace"><strong>Papers and Pre-prints:
</strong><a href="https://www.researchgate.net/profile/Timothy_Dodwell" title="https://www.researchgate.net/profile/Timothy_Dodwell Cmd+Click or tap to follow the link" tabindex="-1" disabled="true" id="LPNoLP">@Research-Gate</a></span></p>
<p><span style="font-family:'Courier New',monospace"><strong>Citations: </strong>
<a href="https://scholar.google.co.uk/citations?user=lPpjRfUAAAAJ&hl=en" title="https://scholar.google.co.uk/citations?user=lPpjRfUAAAAJ&hl=en Cmd+Click or tap to follow the link" id="LPNoLP">@Google-Scholar</a></span></p>
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