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<A NAME="PCMG"><H1>PCMG</H1></A>
Use geometric multigrid preconditioning. This preconditioner requires you provide additional information about the coarser grid matrices and restriction/interpolation operators.
<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>-pc_mg_levels <nlevels> </B></TD><TD>- number of levels including finest
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-pc_mg_cycles 1 or 2 </B></TD><TD>- for V or W-cycle
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-pc_mg_smoothup <n> </B></TD><TD>- number of smoothing steps before interpolation
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-pc_mg_smoothdown <n> </B></TD><TD>- number of smoothing steps before applying restriction operator
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-pc_mg_type <additive,multiplicative,full,cascade> </B></TD><TD>- multiplicative is the default
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-pc_mg_log </B></TD><TD>- log information about time spent on each level of the solver
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-pc_mg_monitor </B></TD><TD>- print information on the multigrid convergence
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-pc_mg_dump_matlab </B></TD><TD>- dumps the matrices for each level and the restriction/interpolation matrices
to the Socket viewer for reading from Matlab.
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
<P>
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../PC/PCCreate.html#PCCreate">PCCreate</A>(), <A HREF="../PC/PCSetType.html#PCSetType">PCSetType</A>(), <A HREF="../PC/PCType.html#PCType">PCType</A> (for list of available types), <A HREF="../PC/PC.html#PC">PC</A>, PCMGType,
<BR><A HREF="../PC/MGSetLevels.html#MGSetLevels">MGSetLevels</A>(), <A HREF="../PC/MGGetLevels.html#MGGetLevels">MGGetLevels</A>(), <A HREF="../PC/MGSetType.html#MGSetType">MGSetType</A>(), MPSetCycles(), <A HREF="../PC/MGSetNumberSmoothDown.html#MGSetNumberSmoothDown">MGSetNumberSmoothDown</A>(),
<A HREF="../PC/MGSetNumberSmoothUp.html#MGSetNumberSmoothUp">MGSetNumberSmoothUp</A>(), <A HREF="../PC/MGGetCoarseSolve.html#MGGetCoarseSolve">MGGetCoarseSolve</A>(), <A HREF="../PC/MGSetResidual.html#MGSetResidual">MGSetResidual</A>(), MGSetInterpolation(),
<A HREF="../PC/MGSetRestriction.html#MGSetRestriction">MGSetRestriction</A>(), <A HREF="../PC/MGGetSmoother.html#MGGetSmoother">MGGetSmoother</A>(), <A HREF="../PC/MGGetSmootherUp.html#MGGetSmootherUp">MGGetSmootherUp</A>(), <A HREF="../PC/MGGetSmootherDown.html#MGGetSmootherDown">MGGetSmootherDown</A>(),
<A HREF="../PC/MGSetCyclesOnLevel.html#MGSetCyclesOnLevel">MGSetCyclesOnLevel</A>(), <A HREF="../PC/MGSetRhs.html#MGSetRhs">MGSetRhs</A>(), <A HREF="../PC/MGSetX.html#MGSetX">MGSetX</A>(), <A HREF="../PC/MGSetR.html#MGSetR">MGSetR</A>()
<P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>intermediate
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/ksp/pc/impls/mg/mg.c.html#PCMG">src/ksp/pc/impls/mg/mg.c</A>
<BR><A HREF="./index.html">Index of all PC routines</A>
<BR><A HREF="../../index.html">Table of Contents for all manual pages</A>
<BR><A HREF="../singleindex.html">Index of all manual pages</A>
<P><H3><FONT COLOR="#CC3333">Examples</FONT></H3>
<A HREF="../../../src/snes/examples/tutorials/ex29.c.html">src/snes/examples/tutorials/ex29.c.html</A><BR>
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