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<div id="version" align=right><b>petsc-3.7.5 2017-01-01</b></div>
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<A NAME="KSPSetCheckNormIteration"><H1>KSPSetCheckNormIteration</H1></A>
Sets the first iteration at which the norm of the residual will be computed and used in the convergence test.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscksp.h"
PetscErrorCode KSPSetCheckNormIteration(KSP ksp,PetscInt it)
</PRE>
Logically Collective on <A HREF="../KSP/KSP.html#KSP">KSP</A>
<P>
<H3><FONT COLOR="#CC3333">Input Parameter</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ksp </B></TD><TD>- Krylov solver context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>it </B></TD><TD>- use -1 to check at all iterations
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
Currently only works with <A HREF="../KSP/KSPCG.html#KSPCG">KSPCG</A>, <A HREF="../KSP/KSPBCGS.html#KSPBCGS">KSPBCGS</A> and <A HREF="../KSP/KSPIBCGS.html#KSPIBCGS">KSPIBCGS</A>
<P>
Use <A HREF="../KSP/KSPSetNormType.html#KSPSetNormType">KSPSetNormType</A>(ksp,<A HREF="../KSP/KSP_NORM_NONE.html#KSP_NORM_NONE">KSP_NORM_NONE</A>) to never check the norm
<P>
On steps where the norm is not computed, the previous norm is still in the variable, so if you run with, for example,
-ksp_monitor the residual norm will appear to be unchanged for several iterations (though it is not really unchanged).
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
<A HREF="../KSP/KSP.html#KSP">KSP</A>, create, context, norms
<BR>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../KSP/KSPSetUp.html#KSPSetUp">KSPSetUp</A>(), <A HREF="../KSP/KSPSolve.html#KSPSolve">KSPSolve</A>(), <A HREF="../KSP/KSPDestroy.html#KSPDestroy">KSPDestroy</A>(), <A HREF="../KSP/KSPConvergedSkip.html#KSPConvergedSkip">KSPConvergedSkip</A>(), <A HREF="../KSP/KSPSetNormType.html#KSPSetNormType">KSPSetNormType</A>()
<BR><P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>advanced
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/ksp/ksp/interface/itcreate.c.html#KSPSetCheckNormIteration">src/ksp/ksp/interface/itcreate.c</A>
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