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<TITLE>PetscConvEstGetConvRate</TITLE>
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<div id="version" align=right><b>petsc-3.14.5 2021-03-03</b></div>
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<A NAME="PetscConvEstGetConvRate"><H1>PetscConvEstGetConvRate</H1></A>
Returns an estimate of the convergence rate for the discretization
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscconvest.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../SNES/PetscConvEstGetConvRate.html#PetscConvEstGetConvRate">PetscConvEstGetConvRate</A>(PetscConvEst ce, <A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> alpha[])
</PRE>
Not collective
<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>ce </B></TD><TD>- The PetscConvEst object
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Output Parameter</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>alpha </B></TD><TD>- The convergence rate for each field
</TD></TR></TABLE>
<P>
Note: The convergence rate alpha is defined by
<pre>
|| u_\Delta - u_exact || < C \Delta^alpha
</pre>
where u_\Delta is the discrete solution, and Delta is a measure of the discretization size. We usually use h for the
spatial resolution and \Delta t for the temporal resolution.
<P>
We solve a series of problems using increasing resolution (refined meshes or decreased timesteps), calculate an error
based upon the exact solution in the DS, and then fit the result to our model above using linear regression.
<P>
<H3><FONT COLOR="#CC3333">Options database keys</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_convergence_estimate : Execute convergence estimation inside <A HREF="../SNES/SNESSolve.html#SNESSolve">SNESSolve</A>() and print out the rate</B></TD>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ts_convergence_estimate : Execute convergence estimation inside <A HREF="../TS/TSSolve.html#TSSolve">TSSolve</A>() and print out the rate</B></TD></TABLE>
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../SNES/PetscConvEstSetSolver.html#PetscConvEstSetSolver">PetscConvEstSetSolver</A>(), <A HREF="../SNES/PetscConvEstCreate.html#PetscConvEstCreate">PetscConvEstCreate</A>(), <A HREF="../SNES/PetscConvEstGetConvRate.html#PetscConvEstGetConvRate">PetscConvEstGetConvRate</A>(), <A HREF="../SNES/SNESSolve.html#SNESSolve">SNESSolve</A>(), <A HREF="../TS/TSSolve.html#TSSolve">TSSolve</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/snes/utils/convest.c.html#PetscConvEstGetConvRate">src/snes/utils/convest.c</A>
<BR><A HREF="./index.html">Index of all SNES routines</A>
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