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<div id="version" align=right><b>slepc-3.23.1 2025-05-01</b></div>
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<H1>DSSetParallel</H1>
Selects the mode of operation in parallel runs.
<H3><FONT COLOR="#883300">Synopsis</FONT></H3>
<PRE>
#include "slepcds.h"
<A HREF="https://petsc.org/release/manualpages/Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../DS/DSSetParallel.html#DSSetParallel">DSSetParallel</A>(<A HREF="../DS/DS.html#DS">DS</A> ds,<A HREF="../DS/DSParallelType.html#DSParallelType">DSParallelType</A> pmode)
</PRE>
Logically Collective
<P>
<H3><FONT COLOR="#883300">Input Parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ds </B></TD><TD> - the direct solver context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>pmode </B></TD><TD> - the parallel mode
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Options Database Key</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ds_parallel <mode> </B></TD><TD> - Sets the parallel mode, 'redundant', 'synchronized'
or 'distributed'
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
In the 'redundant' parallel mode, all processes will make the computation
redundantly, starting from the same data, and producing the same result.
This result may be slightly different in the different processes if using a
multithreaded BLAS library, which may cause issues in ill-conditioned problems.
<P>
In the 'synchronized' parallel mode, only the first MPI process performs the
computation and then the computed quantities are broadcast to the other
processes in the communicator. This communication is not done automatically,
an explicit call to <A HREF="../DS/DSSynchronize.html#DSSynchronize">DSSynchronize</A>() is required.
<P>
The 'distributed' parallel mode can be used in some <A HREF="../DS/DS.html#DS">DS</A> types only, such
as the contour integral method of <A HREF="../DS/DSNEP.html#DSNEP">DSNEP</A>. In this case, every MPI process
will be in charge of part of the computation.
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../DS/DSSynchronize.html#DSSynchronize">DSSynchronize</A>(), <A HREF="../DS/DSGetParallel.html#DSGetParallel">DSGetParallel</A>()
<BR><P><B></B><H3><FONT COLOR="#883300">Level</FONT></H3>advanced<BR>
<H3><FONT COLOR="#883300">Location</FONT></H3>
</B><A HREF="../../../src/sys/classes/ds/interface/dsbasic.c.html#DSSetParallel">src/sys/classes/ds/interface/dsbasic.c</A>
<BR><BR><A HREF="./index.html">Index of all DS routines</A>
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