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<A NAME="MatZeroRowsLocal"><H1>MatZeroRowsLocal</H1></A>
Zeros all entries (except possibly the main diagonal) of a set of rows of a matrix; using local numbering of rows.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscmat.h"
int MatZeroRowsLocal(Mat mat,IS is,const PetscScalar *diag)
</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>is </B></TD><TD>- index set of rows to remove
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>diag </B></TD><TD>- pointer to value put in all diagonals of eliminated rows.
Note that diag is not a pointer to an array, but merely a
pointer to a single value.
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
Before calling <A HREF="../Mat/MatZeroRowsLocal.html#MatZeroRowsLocal">MatZeroRowsLocal</A>(), the user must first set the
local-to-global mapping by calling <A HREF="../Mat/MatSetLocalToGlobalMapping.html#MatSetLocalToGlobalMapping">MatSetLocalToGlobalMapping</A>().
<P>
For the AIJ matrix formats this removes the old nonzero structure,
but does not release memory. For the dense and block diagonal
formats this does not alter the nonzero structure.
<P>
If the option <A HREF="../Mat/MatSetOption.html#MatSetOption">MatSetOption</A>(mat,MAT_KEEP_ZEROED_ROWS) the nonzero structure
of the matrix is not changed (even for AIJ and BAIJ matrices) the values are
merely zeroed.
<P>
The user can set a value in the diagonal entry (or for the AIJ and
row formats can optionally remove the main diagonal entry from the
nonzero structure as well, by passing a null pointer (<A HREF="../Sys/PETSC_NULL.html#PETSC_NULL">PETSC_NULL</A>
in C or PETSC_NULL_SCALAR in Fortran) as the final argument).
<P>
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../Mat/MatZeroEntries.html#MatZeroEntries">MatZeroEntries</A>(), <A HREF="../Mat/MatZeroRows.html#MatZeroRows">MatZeroRows</A>(), <A HREF="../Mat/MatSetLocalToGlobalMapping.html#MatSetLocalToGlobalMapping">MatSetLocalToGlobalMapping</A>
<BR><P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>intermediate
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/mat/interface/matrix.c.html#MatZeroRowsLocal">src/mat/interface/matrix.c</A>
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