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<A NAME="KSPDGMRES"><H1>KSPDGMRES</H1></A>
Implements the deflated GMRES as defined in [1,2]; In this implementation, the adaptive strategy allows to switch to the deflated GMRES when the stagnation occurs. GMRES Options Database Keys: +   -ksp_gmres_restart &lt;restart&gt; - the number of Krylov directions to orthogonalize against .   -ksp_gmres_haptol &lt;tol&gt; - sets the tolerance for "happy ending" (exact convergence) .   -ksp_gmres_preallocate - preallocate all the Krylov search directions initially (otherwise groups of vectors are allocated as needed) .   -ksp_gmres_classicalgramschmidt - use classical (unmodified) Gram-Schmidt to orthogonalize against the Krylov space (fast) (the default) .   -ksp_gmres_modifiedgramschmidt - use modified Gram-Schmidt in the orthogonalization (more stable, but slower) .   -ksp_gmres_cgs_refinement_type &lt;never,ifneeded,always&gt; - determine if iterative refinement is used to increase the stability of the classical Gram-Schmidt  orthogonalization. -   -ksp_gmres_krylov_monitor - plot the Krylov space generated DGMRES Options Database Keys: -ksp_dgmres_eigen &lt;neig&gt; - Number of smallest eigenvalues to extract at each restart -ksp_dgmres_max_eigen &lt;max_neig&gt; - Maximum number of eigenvalues that can be extracted during the iterative process -ksp_dgmres_force &lt;0, 1&gt; - Use the deflation at each restart; switch off the adaptive strategy. 
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Notes: Left and right preconditioning are supported, but not symmetric preconditioning. Complex arithmetic is not yet supported
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<H3><FONT COLOR="#CC3333">References</FONT></H3>
[1]Restarted GMRES preconditioned by deflation,J. Computational and Applied Mathematics, 69(1996), 303-318.
[2]On the performance of various adaptive preconditioned GMRES strategies, 5(1998), 101-121.
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Contributed by: Desire NUENTSA WAKAM,INRIA
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<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/KSPFGMRES.html#KSPFGMRES">KSPFGMRES</A>, <A HREF="../KSP/KSPLGMRES.html#KSPLGMRES">KSPLGMRES</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/KSPGMRESSetOrthogonalization.html#KSPGMRESSetOrthogonalization">KSPGMRESSetOrthogonalization</A>(), <A HREF="../KSP/KSPGMRESGetOrthogonalization.html#KSPGMRESGetOrthogonalization">KSPGMRESGetOrthogonalization</A>(),
<A HREF="../KSP/KSPGMRESClassicalGramSchmidtOrthogonalization.html#KSPGMRESClassicalGramSchmidtOrthogonalization">KSPGMRESClassicalGramSchmidtOrthogonalization</A>(), <A HREF="../KSP/KSPGMRESModifiedGramSchmidtOrthogonalization.html#KSPGMRESModifiedGramSchmidtOrthogonalization">KSPGMRESModifiedGramSchmidtOrthogonalization</A>(),
<A HREF="../KSP/KSPGMRESCGSRefinementType.html#KSPGMRESCGSRefinementType">KSPGMRESCGSRefinementType</A>, <A HREF="../KSP/KSPGMRESSetCGSRefinementType.html#KSPGMRESSetCGSRefinementType">KSPGMRESSetCGSRefinementType</A>(), <A HREF="../KSP/KSPGMRESGetCGSRefinementType.html#KSPGMRESGetCGSRefinementType">KSPGMRESGetCGSRefinementType</A>(), <A HREF="../KSP/KSPGMRESMonitorKrylov.html#KSPGMRESMonitorKrylov">KSPGMRESMonitorKrylov</A>(), <A HREF="../KSP/KSPSetPCSide.html#KSPSetPCSide">KSPSetPCSide</A>()
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<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/dgmres/dgmres.c.html#KSPDGMRES">src/ksp/ksp/impls/gmres/dgmres/dgmres.c</A>
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