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<div id="version" align=right><b>petsc-3.10.3 2018-12-18</b></div>
<div id="bugreport" align=right><a href="mailto:petsc-maint@mcs.anl.gov?subject=Typo or Error in Documentation &body=Please describe the typo or error in the documentation: petsc-3.10.3 v3.10.3 docs/manualpages/KSP/KSPSetPCSide.html "><small>Report Typos and Errors</small></a></div>
<A NAME="KSPSetPCSide"><H1>KSPSetPCSide</H1></A>
Sets the preconditioning side.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscksp.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../KSP/KSPSetPCSide.html#KSPSetPCSide">KSPSetPCSide</A>(<A HREF="../KSP/KSP.html#KSP">KSP</A> ksp,<A HREF="../PC/PCSide.html#PCSide">PCSide</A> side)
</PRE>
Logically Collective on <A HREF="../KSP/KSP.html#KSP">KSP</A>
<P>
<H3><FONT COLOR="#CC3333">Input Parameter</FONT></H3>
<DT><B>ksp </B> -iterative context obtained from <A HREF="../KSP/KSPCreate.html#KSPCreate">KSPCreate</A>()
<br>
<P>
<H3><FONT COLOR="#CC3333">Output Parameter</FONT></H3>
<DT><B>side </B> -the preconditioning side, where side is one of
<br>
<PRE>
<A HREF="../PC/PCSide.html#PCSide">PC_LEFT</A> - left preconditioning (default)
<A HREF="../PC/PCSide.html#PCSide">PC_RIGHT</A> - right preconditioning
<A HREF="../PC/PCSide.html#PCSide">PC_SYMMETRIC</A> - symmetric preconditioning
</PRE>
<P>
<H3><FONT COLOR="#CC3333">Options Database Keys</FONT></H3>
<DT><B>-ksp_pc_side <right,left,symmetric></B> -
Notes:
Left preconditioning is used by default for most Krylov methods except <A HREF="../KSP/KSPFGMRES.html#KSPFGMRES">KSPFGMRES</A> which only supports right preconditioning.
<br>
<P>
For methods changing the side of the preconditioner changes the norm type that is used, see <A HREF="../KSP/KSPSetNormType.html#KSPSetNormType">KSPSetNormType</A>().
<P>
Symmetric preconditioning is currently available only for the <A HREF="../KSP/KSPQCG.html#KSPQCG">KSPQCG</A> method. Note, however, that
symmetric preconditioning can be emulated by using either right or left
preconditioning and a pre or post processing step.
<P>
Setting the <A HREF="../PC/PC.html#PC">PC</A> side often affects the default norm type. See <A HREF="../KSP/KSPSetNormType.html#KSPSetNormType">KSPSetNormType</A>() for details.
<P>
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
set, right, left, symmetric, side, preconditioner, flag
<BR>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../KSP/KSPGetPCSide.html#KSPGetPCSide">KSPGetPCSide</A>(), <A HREF="../KSP/KSPSetNormType.html#KSPSetNormType">KSPSetNormType</A>(), <A HREF="../KSP/KSPGetNormType.html#KSPGetNormType">KSPGetNormType</A>(), <A HREF="../KSP/KSP.html#KSP">KSP</A>
<BR><P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>intermediate<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/ksp/ksp/interface/itfunc.c.html#KSPSetPCSide">src/ksp/ksp/interface/itfunc.c</A>
<BR><A HREF="./index.html">Index of all KSP routines</A>
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