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<TITLE>MatSchurComplementSetAinvType</TITLE>
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<div id="version" align=right><b>petsc-3.7.5 2017-01-01</b></div>
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<A NAME="MatSchurComplementSetAinvType"><H1>MatSchurComplementSetAinvType</H1></A>
set the type of approximation used for the inverse of the (0,0) block used in forming Sp in <A HREF="../KSP/MatSchurComplementGetPmat.html#MatSchurComplementGetPmat">MatSchurComplementGetPmat</A>()
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscksp.h"
PetscErrorCode MatSchurComplementSetAinvType(Mat S,MatSchurComplementAinvType ainvtype)
</PRE>
Not collective.
<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>S </B></TD><TD>- matrix obtained with <A HREF="../KSP/MatCreateSchurComplement.html#MatCreateSchurComplement">MatCreateSchurComplement</A>() (or equivalent) and implementing the action of A11 - A10 ksp(A00,Ap00) A01
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ainvtype </B></TD><TD>- type of approximation used to form A00inv from A00 when assembling Sp = A11 - A10 A00inv A01:
MAT_SCHUR_COMPLEMENT_AINV_DIAG or MAT_SCHUR_COMPLEMENT_AINV_LUMP
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Options database</FONT></H3>
-mat_schur_complement_ainv_type diag | lump
<P>
<H3><FONT COLOR="#CC3333">Note</FONT></H3>
Since the real Schur complement is usually dense, providing a good approximation to newpmat usually requires
application-specific information. The default for assembled matrices is to use the inverse of the diagonal of
the (0,0) block A00 in place of A00^{-1}. This rarely produces a scalable algorithm. Optionally, A00 can be lumped
before forming inv(diag(A00)).
<P>
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../KSP/MatSchurComplementAinvType.html#MatSchurComplementAinvType">MatSchurComplementAinvType</A>, <A HREF="../KSP/MatCreateSchurComplement.html#MatCreateSchurComplement">MatCreateSchurComplement</A>(), <A HREF="../KSP/MatGetSchurComplement.html#MatGetSchurComplement">MatGetSchurComplement</A>(), <A HREF="../KSP/MatSchurComplementGetPmat.html#MatSchurComplementGetPmat">MatSchurComplementGetPmat</A>(), <A HREF="../KSP/MatSchurComplementGetAinvType.html#MatSchurComplementGetAinvType">MatSchurComplementGetAinvType</A>()
<BR><P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>advanced
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/ksp/ksp/utils/schurm.c.html#MatSchurComplementSetAinvType">src/ksp/ksp/utils/schurm.c</A>
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