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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="MatAssemblyBegin"><H1>MatAssemblyBegin</H1></A>
Begins assembling the matrix. This routine should be called after completing all calls to <A HREF="../Mat/MatSetValues.html#MatSetValues">MatSetValues</A>().
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscmat.h"
PetscErrorCode MatAssemblyBegin(Mat mat,MatAssemblyType type)
</PRE>
Collective on <A HREF="../Mat/Mat.html#Mat">Mat</A>
<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>mat </B></TD><TD>- the matrix
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>type </B></TD><TD>- type of assembly, either MAT_FLUSH_ASSEMBLY or MAT_FINAL_ASSEMBLY
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
<A HREF="../Mat/MatSetValues.html#MatSetValues">MatSetValues</A>() generally caches the values. The matrix is ready to
use only after <A HREF="../Mat/MatAssemblyBegin.html#MatAssemblyBegin">MatAssemblyBegin</A>() and <A HREF="../Mat/MatAssemblyEnd.html#MatAssemblyEnd">MatAssemblyEnd</A>() have been called.
Use MAT_FLUSH_ASSEMBLY when switching between <A HREF="../Sys/ADD_VALUES.html#ADD_VALUES">ADD_VALUES</A> and <A HREF="../Sys/INSERT_VALUES.html#INSERT_VALUES">INSERT_VALUES</A>
in <A HREF="../Mat/MatSetValues.html#MatSetValues">MatSetValues</A>(); use MAT_FINAL_ASSEMBLY for the final assembly before
using the matrix.
<P>
ALL processes that share a matrix MUST call <A HREF="../Mat/MatAssemblyBegin.html#MatAssemblyBegin">MatAssemblyBegin</A>() and <A HREF="../Mat/MatAssemblyEnd.html#MatAssemblyEnd">MatAssemblyEnd</A>() the SAME NUMBER of times, and each time with the
same flag of MAT_FLUSH_ASSEMBLY or MAT_FINAL_ASSEMBLY for all processes. Thus you CANNOT locally change from <A HREF="../Sys/ADD_VALUES.html#ADD_VALUES">ADD_VALUES</A> to <A HREF="../Sys/INSERT_VALUES.html#INSERT_VALUES">INSERT_VALUES</A>, that is
a global collective operation requring all processes that share the matrix.
<P>
Space for preallocated nonzeros that is not filled by a call to <A HREF="../Mat/MatSetValues.html#MatSetValues">MatSetValues</A>() or a related routine are compressed
out by assembly. If you intend to use that extra space on a subsequent assembly, be sure to insert explicit zeros
before MAT_FINAL_ASSEMBLY so the space is not compressed out.
<P>
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../Mat/MatAssemblyEnd.html#MatAssemblyEnd">MatAssemblyEnd</A>(), <A HREF="../Mat/MatSetValues.html#MatSetValues">MatSetValues</A>(), <A HREF="../Mat/MatAssembled.html#MatAssembled">MatAssembled</A>()
<BR><P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>beginner
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/mat/interface/matrix.c.html#MatAssemblyBegin">src/mat/interface/matrix.c</A>
<BR><A HREF="./index.html">Index of all Mat routines</A>
<BR><A HREF="../../index.html">Table of Contents for all manual pages</A>
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<P><H3><FONT COLOR="#CC3333">Examples</FONT></H3>
<A HREF="../../../src/mat/examples/tutorials/ex2.c.html">src/mat/examples/tutorials/ex2.c.html</A><BR>
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<A HREF="../../../src/mat/examples/tutorials/ex12.c.html">src/mat/examples/tutorials/ex12.c.html</A><BR>
<A HREF="../../../src/mat/examples/tutorials/ex15.c.html">src/mat/examples/tutorials/ex15.c.html</A><BR>
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<A HREF="../../../src/mat/examples/tutorials/ex17.c.html">src/mat/examples/tutorials/ex17.c.html</A><BR>
<A HREF="../../../src/ksp/pc/examples/tutorials/ex1.c.html">src/ksp/pc/examples/tutorials/ex1.c.html</A><BR>
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