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<div id="version" align=right><b>petsc-3.4.2 2013-07-02</b></div>
<A NAME="KSPSPECEST"><H1>KSPSPECEST</H1></A>
Estimate the spectrum on the first <A HREF="../KSP/KSPSolve.html#KSPSolve">KSPSolve</A>, then use cheaper smoother for subsequent solves.
<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>-ksp_specest_minfactor <0.9> </B></TD><TD>- Multiplier on the minimum eigen/singular value
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ksp_specest_maxfactor <1.1> </B></TD><TD>- Multiplier on the maximum eigen/singular value
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ksp_specest_richfactor <1> </B></TD><TD>- Multiplier on the richimum eigen/singular value
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-specest_ksp_type <type> </B></TD><TD>- <A HREF="../KSP/KSP.html#KSP">KSP</A> used to estimate the spectrum (usually CG or GMRES)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-speccheap_ksp_type <type> </B></TD><TD>- <A HREF="../KSP/KSP.html#KSP">KSP</A> used as a cheap smoother once the spectrum has been estimated (usually Chebyshev or Richardson)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>see <A HREF="../KSP/KSPSolve.html#KSPSolve">KSPSolve</A>() for more</B></TD><TD>-
Notes:
This <A HREF="../KSP/KSP.html#KSP">KSP</A> estimates the extremal singular values on the first pass, then uses them to configure a smoother that
uses fewer dot products. It is intended for use on the levels of multigrid, especially at high process counts,
where dot products are very expensive.
</TD></TR></TABLE>
<P>
The same <A HREF="../PC/PC.html#PC">PC</A> is used for both the estimator and the cheap smoother, it is only set up once. There are no options
keys for -specest_pc_ or speccheap_pc_ since it is the same object as -pc_.
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../KSP/KSPCreate.html#KSPCreate">KSPCreate</A>(), <A HREF="../KSP/KSPSetType.html#KSPSetType">KSPSetType</A>(), <A HREF="../KSP/KSPType.html#KSPType">KSPType</A> (for list of available types), <A HREF="../KSP/KSP.html#KSP">KSP</A>, <A HREF="../KSP/KSPGMRES.html#KSPGMRES">KSPGMRES</A>, <A HREF="../KSP/KSPCG.html#KSPCG">KSPCG</A>, <A HREF="../KSP/KSPCHEBYSHEV.html#KSPCHEBYSHEV">KSPCHEBYSHEV</A>, <A HREF="../KSP/KSPRICHARDSON.html#KSPRICHARDSON">KSPRICHARDSON</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/specest/specest.c.html#KSPSPECEST">src/ksp/ksp/impls/specest/specest.c</A>
<BR><A HREF="./index.html">Index of all KSP routines</A>
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