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<div id="version" align=right><b>petsc-3.7.5 2017-01-01</b></div>
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<A NAME="KSPPIPEFGMRES"><H1>KSPPIPEFGMRES</H1></A>
Implements the Pipelined Generalized Minimal Residual method. A Flexible, 1-stage pipelined variant of GMRES
<P>
This variant is not "explicitly normalized" like PGMRES, and requires a shift parameter.
<P>
A heuristic for choosing the shift parameter is the largest eigenvalue of the preconditioned operator.
<P>
Only right preconditioning is supported (but this preconditioner may be nonlinear, as with FGMRES)
<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>-ksp_gmres_restart <restart> </B></TD><TD>- the number of Krylov directions to orthogonalize against
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ksp_gmres_haptol <tol> </B></TD><TD>- sets the tolerance for "happy ending" (exact convergence)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ksp_gmres_preallocate </B></TD><TD>- preallocate all the Krylov search directions initially (otherwise groups of
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ksp_pipefgmres_shift </B></TD><TD>- the shift to use (defaults to 1. See <A HREF="../KSP/KSPPIPEFGMRESSetShift.html#KSPPIPEFGMRESSetShift">KSPPIPEFGMRESSetShift</A>()
vectors are allocated as needed)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ksp_gmres_krylov_monitor </B></TD><TD>- plot the Krylov space generated
</TD></TR></TABLE>
<P>
<P>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
MPI configuration may be necessary for reductions to make asynchronous progress, which is important for performance of pipelined methods.
See the FAQ on the PETSc website for details.
<P>
Developer Notes: This object is subclassed off of <A HREF="../KSP/KSPGMRES.html#KSPGMRES">KSPGMRES</A>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../KSP/KSPCreate.html#KSPCreate">KSPCreate</A>(), <A HREF="../KSP/KSPSetType.html#KSPSetType">KSPSetType</A>(), <A HREF="../KSP/KSPType.html#KSPType">KSPType</A> (for list of available types), <A HREF="../KSP/KSP.html#KSP">KSP</A>, <A HREF="../KSP/KSPLGMRES.html#KSPLGMRES">KSPLGMRES</A>, <A HREF="../KSP/KSPPIPECG.html#KSPPIPECG">KSPPIPECG</A>, <A HREF="../KSP/KSPPIPECR.html#KSPPIPECR">KSPPIPECR</A>, <A HREF="../KSP/KSPPGMRES.html#KSPPGMRES">KSPPGMRES</A>, <A HREF="../KSP/KSPFGMRES.html#KSPFGMRES">KSPFGMRES</A>
<BR><A HREF="../KSP/KSPGMRESSetRestart.html#KSPGMRESSetRestart">KSPGMRESSetRestart</A>(), <A HREF="../KSP/KSPGMRESSetHapTol.html#KSPGMRESSetHapTol">KSPGMRESSetHapTol</A>(), <A HREF="../KSP/KSPGMRESSetPreAllocateVectors.html#KSPGMRESSetPreAllocateVectors">KSPGMRESSetPreAllocateVectors</A>(), <A HREF="../KSP/KSPGMRESMonitorKrylov.html#KSPGMRESMonitorKrylov">KSPGMRESMonitorKrylov</A>(), KSPPIPEGMRESSetShift()
<P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>beginner
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/ksp/ksp/impls/gmres/pipefgmres/pipefgmres.c.html#KSPPIPEFGMRES">src/ksp/ksp/impls/gmres/pipefgmres/pipefgmres.c</A>
<BR><A HREF="./index.html">Index of all KSP 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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