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<TITLE>SNESNGMRES</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/SNESNGMRES.html "><small>Report Typos and Errors</small></a></div>
<A NAME="SNESNGMRES"><H1>SNESNGMRES</H1></A>
The Nonlinear Generalized Minimum Residual method.
<P>
<H3><FONT COLOR="#CC3333">Options Database</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_select_type<difference,none,linesearch> </B></TD><TD>- choose the select between candidate and combined solution
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_restart_type<difference,none,periodic> </B></TD><TD>- choose the restart conditions
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_candidate </B></TD><TD>- Use NGMRES variant which combines candidate solutions instead of actual solutions
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_m </B></TD><TD>- Number of stored previous solutions and residuals
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_restart_it </B></TD><TD>- Number of iterations the restart conditions hold before restart
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_gammaA </B></TD><TD>- Residual tolerance for solution select between the candidate and combination
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_gammaC </B></TD><TD>- Residual tolerance for restart
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_epsilonB </B></TD><TD>- Difference tolerance between subsequent solutions triggering restart
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_deltaB </B></TD><TD>- Difference tolerance between residuals triggering restart
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_restart_fm_rise </B></TD><TD>- Restart on residual rise from x_M step
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_ngmres_monitor </B></TD><TD>- Prints relevant information about the ngmres iteration
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-snes_linesearch_type <basic,l2,cp> </B></TD><TD>- Line search type used for the default smoother
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-additive_snes_linesearch_type </B></TD><TD>- linesearch type used to select between the candidate and combined solution with additive select type
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
<P>
The N-GMRES method combines m previous solutions into a minimum-residual solution by solving a small linearized
optimization problem at each iteration.
<P>
Very similar to the <A HREF="../SNES/SNESANDERSON.html#SNESANDERSON">SNESANDERSON</A> algorithm.
<P>
<H3><FONT COLOR="#CC3333">References</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>1. </B></TD><TD>- C. W. Oosterlee and T. Washio, "Krylov Subspace Acceleration of Nonlinear Multigrid with Application to Recirculating Flows",
SIAM Journal on Scientific Computing, 21(5), 2000.
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>2. </B></TD><TD>- Peter R. Brune, Matthew G. Knepley, Barry F. Smith, and Xuemin Tu, "Composing Scalable Nonlinear Algebraic Solvers",
SIAM Review, 57(4), 2015
</TD></TR></TABLE>
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../SNES/SNESCreate.html#SNESCreate">SNESCreate</A>(), <A HREF="../SNES/SNES.html#SNES">SNES</A>, <A HREF="../SNES/SNESSetType.html#SNESSetType">SNESSetType</A>(), <A HREF="../SNES/SNESType.html#SNESType">SNESType</A> (for list of available types)
<BR><P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>beginner
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/snes/impls/ngmres/snesngmres.c.html#SNESNGMRES">src/snes/impls/ngmres/snesngmres.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>
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