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<div id="version" align=right><b>petsc-3.4.2 2013-07-02</b></div>
<A NAME="KSPDefaultConverged"><H1>KSPDefaultConverged</H1></A>
Determines convergence of the iterative solvers (default code).
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscksp.h"
PetscErrorCode KSPDefaultConverged(KSP ksp,PetscInt n,PetscReal rnorm,KSPConvergedReason *reason,void *ctx)
</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
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>n </B></TD><TD>- iteration number
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>rnorm </B></TD><TD>- 2-norm residual value (may be estimated)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ctx </B></TD><TD>- convergence context which must be created by <A HREF="../KSP/KSPDefaultConvergedCreate.html#KSPDefaultConvergedCreate">KSPDefaultConvergedCreate</A>()
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">reason is set to</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>positive </B></TD><TD>- if the iteration has converged;
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>negative </B></TD><TD>- if residual norm exceeds divergence threshold;
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>0 </B></TD><TD>- otherwise.
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
<A HREF="../KSP/KSPDefaultConverged.html#KSPDefaultConverged">KSPDefaultConverged</A>() reaches convergence when
<pre>
rnorm < MAX (rtol * rnorm_0, abstol);
</pre>
Divergence is detected if
<pre>
rnorm > dtol * rnorm_0,
</pre>
<P>
where
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>rtol = relative tolerance,</B></TD><TD>- . abstol = absolute tolerance.
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>dtol = divergence tolerance,</B></TD><TD>- - rnorm_0 is the two norm of the right hand side. When initial guess is non-zero you
can call <A HREF="../KSP/KSPDefaultConvergedSetUIRNorm.html#KSPDefaultConvergedSetUIRNorm">KSPDefaultConvergedSetUIRNorm</A>() to use the norm of (b - A*(initial guess))
as the starting point for relative norm convergence testing.
</TD></TR>
<P>
Use <A HREF="../KSP/KSPSetTolerances.html#KSPSetTolerances">KSPSetTolerances</A>() to alter the defaults for rtol, abstol, dtol.
<P>
The precise values of reason are macros such as <A HREF="../KSP/KSP_CONVERGED_RTOL.html#KSP_CONVERGED_RTOL">KSP_CONVERGED_RTOL</A>, which
are defined in petscksp.h.
<P>
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
<A HREF="../KSP/KSP.html#KSP">KSP</A>, default, convergence, residual
<BR>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../KSP/KSPSetConvergenceTest.html#KSPSetConvergenceTest">KSPSetConvergenceTest</A>(), <A HREF="../KSP/KSPSetTolerances.html#KSPSetTolerances">KSPSetTolerances</A>(), <A HREF="../KSP/KSPSkipConverged.html#KSPSkipConverged">KSPSkipConverged</A>(), <A HREF="../KSP/KSPConvergedReason.html#KSPConvergedReason">KSPConvergedReason</A>, <A HREF="../KSP/KSPGetConvergedReason.html#KSPGetConvergedReason">KSPGetConvergedReason</A>(),
<BR><A HREF="../KSP/KSPDefaultConvergedSetUIRNorm.html#KSPDefaultConvergedSetUIRNorm">KSPDefaultConvergedSetUIRNorm</A>(), <A HREF="../KSP/KSPDefaultConvergedSetUMIRNorm.html#KSPDefaultConvergedSetUMIRNorm">KSPDefaultConvergedSetUMIRNorm</A>(), <A HREF="../KSP/KSPDefaultConvergedCreate.html#KSPDefaultConvergedCreate">KSPDefaultConvergedCreate</A>(), <A HREF="../KSP/KSPDefaultConvergedDestroy.html#KSPDefaultConvergedDestroy">KSPDefaultConvergedDestroy</A>()
<P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>intermediate
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/ksp/ksp/interface/iterativ.c.html#KSPDefaultConverged">src/ksp/ksp/interface/iterativ.c</A>
<BR><A HREF="./index.html">Index of all KSP routines</A>
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