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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="SNESCreate"><H1>SNESCreate</H1></A>
Creates a nonlinear solver context. 
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscsnes.h"  
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A>  <A HREF="../SNES/SNESCreate.html#SNESCreate">SNESCreate</A>(<A HREF="../Sys/MPI_Comm.html#MPI_Comm">MPI_Comm</A> comm,<A HREF="../SNES/SNES.html#SNES">SNES</A> *outsnes)
</PRE>
Collective
<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>comm </B></TD><TD>- MPI communicator
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Output Parameter</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>outsnes </B></TD><TD>- the new <A HREF="../SNES/SNES.html#SNES">SNES</A> context
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Options Database Keys</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_mf </B></TD><TD>- Activates default matrix-free Jacobian-vector products,
and no preconditioning matrix
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_mf_operator </B></TD><TD>- Activates default matrix-free Jacobian-vector
products, and a user-provided preconditioning matrix
as set by <A HREF="../SNES/SNESSetJacobian.html#SNESSetJacobian">SNESSetJacobian</A>()
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_fd </B></TD><TD>- Uses (slow!) finite differences to compute Jacobian
</TD></TR></TABLE>
<P>

<P>
<H3><FONT COLOR="#CC3333">Developer Notes</FONT></H3>
<A HREF="../SNES/SNES.html#SNES">SNES</A> always creates a <A HREF="../KSP/KSP.html#KSP">KSP</A> object even though many <A HREF="../SNES/SNES.html#SNES">SNES</A> methods do not use it. This is
unfortunate and should be fixed at some point. The flag snes-&gt;usesksp indicates if the
particular method does use <A HREF="../KSP/KSP.html#KSP">KSP</A> and regulates if the information about the <A HREF="../KSP/KSP.html#KSP">KSP</A> is printed
in <A HREF="../SNES/SNESView.html#SNESView">SNESView</A>(). <A HREF="../TS/TSSetFromOptions.html#TSSetFromOptions">TSSetFromOptions</A>() does call <A HREF="../SNES/SNESSetFromOptions.html#SNESSetFromOptions">SNESSetFromOptions</A>() which can lead to users being confused
by help messages about meaningless <A HREF="../SNES/SNES.html#SNES">SNES</A> options.
<P>
<A HREF="../SNES/SNES.html#SNES">SNES</A> always creates the snes-&gt;kspconvctx even though it is used by only one type. This should
be fixed.
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
 <A HREF="../SNES/SNESSolve.html#SNESSolve">SNESSolve</A>(), <A HREF="../SNES/SNESDestroy.html#SNESDestroy">SNESDestroy</A>(), <A HREF="../SNES/SNES.html#SNES">SNES</A>, <A HREF="../SNES/SNESSetLagPreconditioner.html#SNESSetLagPreconditioner">SNESSetLagPreconditioner</A>(), <A HREF="../SNES/SNESSetLagJacobian.html#SNESSetLagJacobian">SNESSetLagJacobian</A>()
<BR>
<P>
<P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>beginner<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/snes/interface/snes.c.html#SNESCreate">src/snes/interface/snes.c</A>
<P><H3><FONT COLOR="#CC3333">Examples</FONT></H3>
<A HREF="../../../src/snes/tutorials/ex1.c.html">src/snes/tutorials/ex1.c.html</A><BR>
<A HREF="../../../src/snes/tutorials/ex2.c.html">src/snes/tutorials/ex2.c.html</A><BR>
<A HREF="../../../src/snes/tutorials/ex3.c.html">src/snes/tutorials/ex3.c.html</A><BR>
<A HREF="../../../src/snes/tutorials/ex5.c.html">src/snes/tutorials/ex5.c.html</A><BR>
<A HREF="../../../src/snes/tutorials/ex9.c.html">src/snes/tutorials/ex9.c.html</A><BR>
<A HREF="../../../src/snes/tutorials/ex12.c.html">src/snes/tutorials/ex12.c.html</A><BR>
<A HREF="../../../src/snes/tutorials/ex14.c.html">src/snes/tutorials/ex14.c.html</A><BR>
<A HREF="../../../src/snes/tutorials/ex15.c.html">src/snes/tutorials/ex15.c.html</A><BR>
<A HREF="../../../src/snes/tutorials/ex17.c.html">src/snes/tutorials/ex17.c.html</A><BR>
<A HREF="../../../src/snes/tutorials/ex18.c.html">src/snes/tutorials/ex18.c.html</A><BR>
<A HREF="../../../src/snes/tutorials/ex19.c.html">src/snes/tutorials/ex19.c.html</A><BR>
<P><H3><FONT COLOR="CC3333">Implementations</FONT></H3><A HREF="../../../src/snes/impls/composite/snescomposite.c.html#SNESCreate_Composite">SNESCreate_Composite in src/snes/impls/composite/snescomposite.c</A><BR>
<A HREF="../../../src/snes/impls/fas/fas.c.html#SNESCreate_FAS">SNESCreate_FAS in src/snes/impls/fas/fas.c</A><BR>
<A HREF="../../../src/snes/impls/gs/snesgs.c.html#SNESCreate_NGS">SNESCreate_NGS in src/snes/impls/gs/snesgs.c</A><BR>
<A HREF="../../../src/snes/impls/ksponly/ksponly.c.html#SNESCreate_KSPONLY">SNESCreate_KSPONLY in src/snes/impls/ksponly/ksponly.c</A><BR>
<A HREF="../../../src/snes/impls/ksponly/ksponly.c.html#SNESCreate_KSPTRANSPOSEONLY">SNESCreate_KSPTRANSPOSEONLY in src/snes/impls/ksponly/ksponly.c</A><BR>
<A HREF="../../../src/snes/impls/ls/ls.c.html#SNESCreate_NEWTONLS">SNESCreate_NEWTONLS in src/snes/impls/ls/ls.c</A><BR>
<A HREF="../../../src/snes/impls/ms/ms.c.html#SNESCreate_MS">SNESCreate_MS in src/snes/impls/ms/ms.c</A><BR>
<A HREF="../../../src/snes/impls/multiblock/multiblock.c.html#SNESCreate_Multiblock">SNESCreate_Multiblock in src/snes/impls/multiblock/multiblock.c</A><BR>
<A HREF="../../../src/snes/impls/nasm/aspin.c.html#SNESCreate_ASPIN">SNESCreate_ASPIN in src/snes/impls/nasm/aspin.c</A><BR>
<A HREF="../../../src/snes/impls/nasm/nasm.c.html#SNESCreate_NASM">SNESCreate_NASM in src/snes/impls/nasm/nasm.c</A><BR>
<A HREF="../../../src/snes/impls/ncg/snesncg.c.html#SNESCreate_NCG">SNESCreate_NCG in src/snes/impls/ncg/snesncg.c</A><BR>
<A HREF="../../../src/snes/impls/ngmres/anderson.c.html#SNESCreate_Anderson">SNESCreate_Anderson in src/snes/impls/ngmres/anderson.c</A><BR>
<A HREF="../../../src/snes/impls/ngmres/snesngmres.c.html#SNESCreate_NGMRES">SNESCreate_NGMRES in src/snes/impls/ngmres/snesngmres.c</A><BR>
<A HREF="../../../src/snes/impls/patch/snespatch.c.html#SNESCreate_Patch">SNESCreate_Patch in src/snes/impls/patch/snespatch.c</A><BR>
<A HREF="../../../src/snes/impls/qn/qn.c.html#SNESCreate_QN">SNESCreate_QN in src/snes/impls/qn/qn.c</A><BR>
<A HREF="../../../src/snes/impls/richardson/snesrichardson.c.html#SNESCreate_NRichardson">SNESCreate_NRichardson in src/snes/impls/richardson/snesrichardson.c</A><BR>
<A HREF="../../../src/snes/impls/shell/snesshell.c.html#SNESCreate_Shell">SNESCreate_Shell in src/snes/impls/shell/snesshell.c</A><BR>
<A HREF="../../../src/snes/impls/tr/tr.c.html#SNESCreate_NEWTONTR">SNESCreate_NEWTONTR in src/snes/impls/tr/tr.c</A><BR>
<A HREF="../../../src/snes/impls/vi/rs/virs.c.html#SNESCreate_VINEWTONRSLS">SNESCreate_VINEWTONRSLS in src/snes/impls/vi/rs/virs.c</A><BR>
<A HREF="../../../src/snes/impls/vi/ss/viss.c.html#SNESCreate_VINEWTONSSLS">SNESCreate_VINEWTONSSLS in src/snes/impls/vi/ss/viss.c</A><BR>
<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>
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