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<TITLE>TSComputeIJacobianConstant</TITLE>
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<div id="version" align=right><b>petsc-3.14.5 2021-03-03</b></div>
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<A NAME="TSComputeIJacobianConstant"><H1>TSComputeIJacobianConstant</H1></A>
Reuses a time-independent for a semi-implicit DAE or ODE
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscts.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../TS/TSComputeIJacobianConstant.html#TSComputeIJacobianConstant">TSComputeIJacobianConstant</A>(<A HREF="../TS/TS.html#TS">TS</A> ts,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> t,<A HREF="../Vec/Vec.html#Vec">Vec</A> U,<A HREF="../Vec/Vec.html#Vec">Vec</A> Udot,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> shift,<A HREF="../Mat/Mat.html#Mat">Mat</A> A,<A HREF="../Mat/Mat.html#Mat">Mat</A> B,void *ctx)
</PRE>
Collective on <A HREF="../TS/TS.html#TS">TS</A>
<P>
<H3><FONT COLOR="#CC3333">Input Arguments</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ts </B></TD><TD>- time stepping context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>t </B></TD><TD>- time at which to evaluate
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>U </B></TD><TD>- state at which to evaluate
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>Udot </B></TD><TD>- time derivative of state vector
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>shift </B></TD><TD>- shift to apply
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ctx </B></TD><TD>- context
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Output Arguments</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>A </B></TD><TD>- pointer to operator
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>B </B></TD><TD>- pointer to preconditioning matrix
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>flg </B></TD><TD>- matrix structure flag
</TD></TR></TABLE>
<P>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
This function is intended to be passed to <A HREF="../TS/TSSetIJacobian.html#TSSetIJacobian">TSSetIJacobian</A>() to evaluate the Jacobian for linear time-independent problems.
<P>
It is only appropriate for problems of the form
<P>
<pre>
M Udot = F(U,t)
</pre>
<P>
where M is constant and F is non-stiff. The user must pass M to <A HREF="../TS/TSSetIJacobian.html#TSSetIJacobian">TSSetIJacobian</A>(). The current implementation only
works with IMEX time integration methods such as <A HREF="../TS/TSROSW.html#TSROSW">TSROSW</A> and <A HREF="../TS/TSARKIMEX.html#TSARKIMEX">TSARKIMEX</A>, since there is no support for de-constructing
an implicit operator of the form
<P>
<pre>
shift*M + J
</pre>
<P>
where J is the Jacobian of -F(U). Support may be added in a future version of PETSc, but for now, the user must store
a copy of M or reassemble it when requested.
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../TS/TSSetIFunction.html#TSSetIFunction">TSSetIFunction</A>(), <A HREF="../TS/TSSetIJacobian.html#TSSetIJacobian">TSSetIJacobian</A>(), <A HREF="../TS/TSComputeIFunctionLinear.html#TSComputeIFunctionLinear">TSComputeIFunctionLinear</A>()
<BR><P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>advanced<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/ts/interface/ts.c.html#TSComputeIJacobianConstant">src/ts/interface/ts.c</A>
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