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<div id="version" align=right><b>petsc-3.10.3 2018-12-18</b></div>
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<A NAME="SNESSetLagJacobian"><H1>SNESSetLagJacobian</H1></A>
Determines when the Jacobian is rebuilt in the nonlinear solve. See <A HREF="../SNES/SNESSetLagPreconditioner.html#SNESSetLagPreconditioner">SNESSetLagPreconditioner</A>() for determining how often the preconditioner is rebuilt.
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscsnes.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../SNES/SNESSetLagJacobian.html#SNESSetLagJacobian">SNESSetLagJacobian</A>(<A HREF="../SNES/SNES.html#SNES">SNES</A> snes,<A HREF="../Sys/PetscInt.html#PetscInt">PetscInt</A> lag)
</PRE>
Logically 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>- the <A HREF="../SNES/SNES.html#SNES">SNES</A> context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>lag </B></TD><TD>- -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
the Jacobian is built etc. -2 means rebuild at next chance but then never again
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Options Database Keys</FONT></H3>
<DT><B>-snes_lag_jacobian <lag></B> -
Notes:
The default is 1
The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
If -1 is used before the very first nonlinear solve the CODE WILL FAIL! because no Jacobian is used, use -2 to indicate you want it recomputed
at the next Newton step but never again (unless it is reset to another value)
<br>
<P>
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
<A HREF="../SNES/SNES.html#SNES">SNES</A>, nonlinear, set, convergence, tolerances
<BR>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../SNES/SNESSetTrustRegionTolerance.html#SNESSetTrustRegionTolerance">SNESSetTrustRegionTolerance</A>(), <A HREF="../SNES/SNESGetLagPreconditioner.html#SNESGetLagPreconditioner">SNESGetLagPreconditioner</A>(), <A HREF="../SNES/SNESSetLagPreconditioner.html#SNESSetLagPreconditioner">SNESSetLagPreconditioner</A>(), <A HREF="../SNES/SNESGetLagJacobian.html#SNESGetLagJacobian">SNESGetLagJacobian</A>()
<BR>
<P>
<P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>intermediate<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/snes/interface/snes.c.html#SNESSetLagJacobian">src/snes/interface/snes.c</A>
<BR><A HREF="./index.html">Index of all SNES routines</A>
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