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<TITLE>SNESComputeJacobianDefaultColor</TITLE>
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<div id="version" align=right><b>petsc-3.7.5 2017-01-01</b></div>
<div id="bugreport" align=right><a href="mailto:petsc-maint@mcs.anl.gov?subject=Typo or Error in Documentation &body=Please describe the typo or error in the documentation: petsc-3.7.5 v3.7.5 docs/manualpages/SNES/SNESComputeJacobianDefaultColor.html "><small>Report Typos and Errors</small></a></div>
<A NAME="SNESComputeJacobianDefaultColor"><H1>SNESComputeJacobianDefaultColor</H1></A>
Computes the Jacobian using finite differences and coloring to exploit matrix sparsity.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscsnes.h"
#include "petscdm.h"
PetscErrorCode SNESComputeJacobianDefaultColor(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
</PRE>
Collective on <A HREF="../SNES/SNES.html#SNES">SNES</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>snes </B></TD><TD>- nonlinear solver object
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>x1 </B></TD><TD>- location at which to evaluate Jacobian
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ctx </B></TD><TD>- <A HREF="../Mat/MatFDColoring.html#MatFDColoring">MatFDColoring</A> context or NULL
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Output Parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>J </B></TD><TD>- Jacobian matrix (not altered in this routine)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>B </B></TD><TD>- newly computed Jacobian matrix to use with preconditioner (generally the same as J)
</TD></TR></TABLE>
<P>
<P>
<H3><FONT COLOR="#CC3333">Options Database Key</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_fd_color_use_mat </B></TD><TD>- use a matrix coloring from the explicit matrix nonzero pattern instead of from the <A HREF="../DM/DM.html#DM">DM</A> providing the matrix
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_fd_color </B></TD><TD>- Activates <A HREF="../SNES/SNESComputeJacobianDefaultColor.html#SNESComputeJacobianDefaultColor">SNESComputeJacobianDefaultColor</A>() in <A HREF="../SNES/SNESSetFromOptions.html#SNESSetFromOptions">SNESSetFromOptions</A>()
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-mat_fd_coloring_err <err> </B></TD><TD>- Sets <err> (square root of relative error in the function)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-mat_fd_coloring_umin <umin> </B></TD><TD>- Sets umin, the minimum allowable u-value magnitude
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-mat_fd_type </B></TD><TD>- Either wp or ds (see <A HREF="../Mat/MATMFFD_WP.html#MATMFFD_WP">MATMFFD_WP</A> or <A HREF="../Mat/MATMFFD_DS.html#MATMFFD_DS">MATMFFD_DS</A>)
</TD></TR></TABLE>
<P>
Notes: If the coloring is not provided through the context, this will first try to get the
coloring from the <A HREF="../DM/DM.html#DM">DM</A>. If the <A HREF="../DM/DM.html#DM">DM</A> type has no coloring routine, then it will try to
get the coloring from the matrix. This requires that the matrix have nonzero entries
precomputed. This is discouraged, as <A HREF="../MatOrderings/MatColoringApply.html#MatColoringApply">MatColoringApply</A>() is not parallel by default.
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
<A HREF="../SNES/SNES.html#SNES">SNES</A>, finite differences, Jacobian, coloring, sparse
<BR>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../SNES/SNESSetJacobian.html#SNESSetJacobian">SNESSetJacobian</A>(), SNESTestJacobian(), <A HREF="../SNES/SNESComputeJacobianDefault.html#SNESComputeJacobianDefault">SNESComputeJacobianDefault</A>()
<BR><A HREF="../MatFD/MatFDColoringCreate.html#MatFDColoringCreate">MatFDColoringCreate</A>(), <A HREF="../MatFD/MatFDColoringSetFunction.html#MatFDColoringSetFunction">MatFDColoringSetFunction</A>()
<P>
<P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>intermediate
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/snes/interface/snesj2.c.html#SNESComputeJacobianDefaultColor">src/snes/interface/snesj2.c</A>
<BR><A HREF="./index.html">Index of all SNES 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/snes/examples/tutorials/ex5s.c.html">src/snes/examples/tutorials/ex5s.c.html</A><BR>
<A HREF="../../../src/snes/examples/tutorials/ex14.c.html">src/snes/examples/tutorials/ex14.c.html</A><BR>
<A HREF="../../../src/ts/examples/tutorials/ex10.c.html">src/ts/examples/tutorials/ex10.c.html</A><BR>
<A HREF="../../../src/ts/examples/tutorials/ex15.c.html">src/ts/examples/tutorials/ex15.c.html</A><BR>
<A HREF="../../../src/ts/examples/tutorials/ex17.c.html">src/ts/examples/tutorials/ex17.c.html</A><BR>
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