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<div id="version" align=right><b>petsc-3.10.3 2018-12-18</b></div>
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<A NAME="MatGalerkin"><H1>MatGalerkin</H1></A>
Constructs the coarse grid problem via Galerkin projection.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscmat.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../Mat/MatGalerkin.html#MatGalerkin">MatGalerkin</A>(<A HREF="../Mat/Mat.html#Mat">Mat</A> restrct, <A HREF="../Mat/Mat.html#Mat">Mat</A> dA, <A HREF="../Mat/Mat.html#Mat">Mat</A> interpolate, <A HREF="../Mat/MatReuse.html#MatReuse">MatReuse</A> reuse, <A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> fill, <A HREF="../Mat/Mat.html#Mat">Mat</A> *A)
</PRE>
If the interpolation and restriction operators are the same, uses <A HREF="../Mat/MatPtAP.html#MatPtAP">MatPtAP</A>.
If they are not the same, use <A HREF="../Mat/MatMatMatMult.html#MatMatMatMult">MatMatMatMult</A>.
<P>
Once the coarse grid problem is constructed, correct for interpolation operators
that are not of full rank, which can legitimately happen in the case of non-nested
geometric multigrid.
<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>restrct </B></TD><TD>- restriction operator
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>dA </B></TD><TD>- fine grid matrix
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>interpolate </B></TD><TD>- interpolation operator
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>reuse </B></TD><TD>- either <A HREF="../Mat/MatReuse.html#MatReuse">MAT_INITIAL_MATRIX</A> or <A HREF="../Mat/MatReuse.html#MatReuse">MAT_REUSE_MATRIX</A>
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>fill </B></TD><TD>- expected fill, use <A HREF="../Sys/PETSC_DEFAULT.html#PETSC_DEFAULT">PETSC_DEFAULT</A> if you do not have a good estimate
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Output Parameters</FONT></H3>
<DT><B>A </B> -the Galerkin coarse matrix
<br>
<P>
<H3><FONT COLOR="#CC3333">Options Database Key</FONT></H3>
<DT><B>-pc_mg_galerkin <both,pmat,mat,none></B> -
<br>
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
MG, multigrid, Galerkin
<BR>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../Mat/MatPtAP.html#MatPtAP">MatPtAP</A>(), <A HREF="../Mat/MatMatMatMult.html#MatMatMatMult">MatMatMatMult</A>()
<BR><P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>developer<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/mat/interface/matrix.c.html#MatGalerkin">src/mat/interface/matrix.c</A>
<BR><A HREF="./index.html">Index of all Mat routines</A>
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