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<TITLE>KSPGMRESSetOrthogonalization</TITLE>
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<A NAME="KSPGMRESSetOrthogonalization"><H1>KSPGMRESSetOrthogonalization</H1></A>
Sets the orthogonalization routine used by GMRES and FGMRES.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscksp.h"
int KSPGMRESSetOrthogonalization(KSP ksp,int (*fcn)(KSP,int))
</PRE>
Collective on <A HREF="../KSP/KSP.html#KSP">KSP</A>
<P>
<H3><FONT COLOR="#CC3333">Input Parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ksp </B></TD><TD>- iterative context obtained from <A HREF="../KSP/KSPCreate.html#KSPCreate">KSPCreate</A>
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>fcn </B></TD><TD>- orthogonalization function
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Calling Sequence of function</FONT></H3>
<pre>
errorcode = int fcn(<A HREF="../KSP/KSP.html#KSP">KSP</A> ksp,int it);
</pre>
<pre>
it is one minus the number of GMRES iterations since last restart;
</pre>
<pre>
i.e. the <A HREF="../Sys/size.html#size">size</A> of Krylov space minus one
</pre>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
Two orthogonalization routines are predefined, including
<P>
KSPGMRESModifiedGramSchmidtOrthogonalization()
<P>
KSPGMRESClassicalGramSchmidtOrthogonalization() - Default. Use <A HREF="../KSP/KSPGMRESSetCGSRefinementType.html#KSPGMRESSetCGSRefinementType">KSPGMRESSetCGSRefinementType</A>() to determine if
iterative refinement is used to increase stability.
<P>
<P>
<H3><FONT COLOR="#CC3333">Options Database Keys</FONT></H3>
<P>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ksp_gmres_unmodifiedgramschmidt </B></TD><TD>- Activates KSPGMRESClassicalGramSchmidtOrthogonalization() (default)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ksp_gmres_modifiedgramschmidt </B></TD><TD>- Activates KSPGMRESModifiedGramSchmidtOrthogonalization()
</TD></TR></TABLE>
<P>
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
<A HREF="../KSP/KSP.html#KSP">KSP</A>, GMRES, set, orthogonalization, Gram-Schmidt, iterative refinement
<BR>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../KSP/KSPGMRESSetRestart.html#KSPGMRESSetRestart">KSPGMRESSetRestart</A>(), <A HREF="../KSP/KSPGMRESSetPreAllocateVectors.html#KSPGMRESSetPreAllocateVectors">KSPGMRESSetPreAllocateVectors</A>(), <A HREF="../KSP/KSPGMRESSetCGSRefinementType.html#KSPGMRESSetCGSRefinementType">KSPGMRESSetCGSRefinementType</A>()
<BR><P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>intermediate
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/ksp/ksp/impls/gmres/gmres2.c.html#KSPGMRESSetOrthogonalization">src/ksp/ksp/impls/gmres/gmres2.c</A>
<BR><A HREF="./index.html">Index of all KSP routines</A>
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