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<div id="version" align=right><b>petsc-3.4.2 2013-07-02</b></div>
<A NAME="MatSetUnfactored"><H1>MatSetUnfactored</H1></A>
Resets a factored matrix to be treated as unfactored.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscmat.h"
PetscErrorCode MatSetUnfactored(Mat mat)
</PRE>
Logically Collective on <A HREF="../Mat/Mat.html#Mat">Mat</A>
<P>
<H3><FONT COLOR="#CC3333">Input Parameter</FONT></H3>
<DT><B>mat </B> -the factored matrix to be reset
<br>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
This routine should be used only with factored matrices formed by in-place
factorization via ILU(0) (or by in-place LU factorization for the <A HREF="../Mat/MATSEQDENSE.html#MATSEQDENSE">MATSEQDENSE</A>
format). This option can save memory, for example, when solving nonlinear
systems with a matrix-free Newton-Krylov method and a matrix-based, in-place
ILU(0) preconditioner.
<P>
Note that one can specify in-place ILU(0) factorization by calling
<PRE>
<A HREF="../PC/PCType.html#PCType">PCType</A>(pc,<A HREF="../PC/PCILU.html#PCILU">PCILU</A>);
PCFactorSeUseInPlace(pc);
</PRE>
or by using the options -pc_type ilu -pc_factor_in_place
<P>
In-place factorization ILU(0) can also be used as a local
solver for the blocks within the block Jacobi or additive Schwarz
methods (runtime option: -sub_pc_factor_in_place). See the discussion
of these preconditioners in the <a href="../../docs/manual.pdf#ch_pc"><A HREF="../PC/PC.html#PC">PC</A> chapter of the users manual</a> for details on setting
local solver options.
<P>
Most users should employ the simplified <A HREF="../KSP/KSP.html#KSP">KSP</A> interface for linear solvers
instead of working directly with matrix algebra routines such as this.
See, e.g., <A HREF="../KSP/KSPCreate.html#KSPCreate">KSPCreate</A>().
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../PC/PCFactorSetUseInPlace.html#PCFactorSetUseInPlace">PCFactorSetUseInPlace</A>()
<BR>
<P>
<P>
<P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>developer
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/mat/interface/matrix.c.html#MatSetUnfactored">src/mat/interface/matrix.c</A>
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