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<div id="version" align=right><b>petsc-3.4.2 2013-07-02</b></div>
<A NAME="DMCreateMatrix"><H1>DMCreateMatrix</H1></A>
Gets empty Jacobian for a <A HREF="../DM/DMDA.html#DMDA">DMDA</A> or DMComposite
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscdm.h"
PetscErrorCode DMCreateMatrix(DM dm,MatType mtype,Mat *mat)
</PRE>
Collective on DM
<P>
<H3><FONT COLOR="#CC3333">Input Parameter</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>dm </B></TD><TD>- the DM object
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>mtype </B></TD><TD>- Supported types are <A HREF="../Mat/MATSEQAIJ.html#MATSEQAIJ">MATSEQAIJ</A>, <A HREF="../Mat/MATMPIAIJ.html#MATMPIAIJ">MATMPIAIJ</A>, <A HREF="../Mat/MATSEQBAIJ.html#MATSEQBAIJ">MATSEQBAIJ</A>, <A HREF="../Mat/MATMPIBAIJ.html#MATMPIBAIJ">MATMPIBAIJ</A>, or
any type which inherits from one of these (such as <A HREF="../Mat/MATAIJ.html#MATAIJ">MATAIJ</A>)
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Output Parameter</FONT></H3>
<DT><B>mat </B> -the empty Jacobian
<br>
<P>
<P>
Notes: This properly preallocates the number of nonzeros in the sparse matrix so you
do not need to do it yourself.
<P>
By default it also sets the nonzero structure and puts in the zero entries. To prevent setting
the nonzero pattern call DMDASetMatPreallocateOnly()
<P>
For structured grid problems, when you call <A HREF="../Mat/MatView.html#MatView">MatView</A>() on this matrix it is displayed using the global natural ordering, NOT in the ordering used
internally by PETSc.
<P>
For structured grid problems, in general it is easiest to use <A HREF="../Mat/MatSetValuesStencil.html#MatSetValuesStencil">MatSetValuesStencil</A>() or <A HREF="../Mat/MatSetValuesLocal.html#MatSetValuesLocal">MatSetValuesLocal</A>() to put values into the matrix because <A HREF="../Mat/MatSetValues.html#MatSetValues">MatSetValues</A>() requires
the indices for the global numbering for DMDAs which is complicated.
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../DM/DMDestroy.html#DMDestroy">DMDestroy</A>(), <A HREF="../DM/DMView.html#DMView">DMView</A>(), <A HREF="../DM/DMCreateGlobalVector.html#DMCreateGlobalVector">DMCreateGlobalVector</A>(), <A HREF="../DM/DMCreateInterpolation.html#DMCreateInterpolation">DMCreateInterpolation</A>()
<BR>
<P>
<P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>beginner
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/dm/interface/dm.c.html#DMCreateMatrix">src/dm/interface/dm.c</A>
<BR><A HREF="./index.html">Index of all DM 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/ksp/ksp/examples/tutorials/ex4.c.html">src/ksp/ksp/examples/tutorials/ex4.c.html</A><BR>
<A HREF="../../../src/ksp/ksp/examples/tutorials/ex31.c.html">src/ksp/ksp/examples/tutorials/ex31.c.html</A><BR>
<A HREF="../../../src/ksp/ksp/examples/tutorials/ex39.c.html">src/ksp/ksp/examples/tutorials/ex39.c.html</A><BR>
<A HREF="../../../src/ksp/ksp/examples/tutorials/ex40.c.html">src/ksp/ksp/examples/tutorials/ex40.c.html</A><BR>
<A HREF="../../../src/ksp/ksp/examples/tutorials/ex42.c.html">src/ksp/ksp/examples/tutorials/ex42.c.html</A><BR>
<A HREF="../../../src/ksp/ksp/examples/tutorials/ex43.c.html">src/ksp/ksp/examples/tutorials/ex43.c.html</A><BR>
<A HREF="../../../src/ksp/ksp/examples/tutorials/ex46.c.html">src/ksp/ksp/examples/tutorials/ex46.c.html</A><BR>
<A HREF="../../../src/ksp/ksp/examples/tutorials/ex49.c.html">src/ksp/ksp/examples/tutorials/ex49.c.html</A><BR>
<A HREF="../../../src/ksp/ksp/examples/tutorials/ex44f.F90.html">src/ksp/ksp/examples/tutorials/ex44f.F90.html</A><BR>
<A HREF="../../../src/snes/examples/tutorials/ex10.c.html">src/snes/examples/tutorials/ex10.c.html</A><BR>
<A HREF="../../../src/snes/examples/tutorials/ex12.c.html">src/snes/examples/tutorials/ex12.c.html</A><BR>
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