petsc-3.7.5 2017-01-01

KSPBCGSL

Implements a slight variant of the Enhanced BiCGStab(L) algorithm in (3) and (2). The variation concerns cases when either kappa0**2 or kappa1**2 is negative due to round-off. Kappa0 has also been pulled out of the denominator in the formula for ghat.

References

	1.	- G.L.G. Sleijpen, H.A. van der Vorst, "An overview of approaches for the stable computation of hybrid BiCG methods", Applied Numerical Mathematics: Transactions f IMACS, 19(3), 1996.
	2.	- G.L.G. Sleijpen, H.A. van der Vorst, D.R. Fokkema, "BiCGStab(L) and other hybrid BiCG methods", Numerical Algorithms, 7, 1994.
	3.	- D.R. Fokkema, "Enhanced implementation of BiCGStab(L) for solving linear systems of equations", preprint from www.citeseer.com.

Contributed by: Joel M. Malard, email jm.malard@pnl.gov

Options Database Keys

	-ksp_bcgsl_ell <ell> Number of Krylov search directions, defaults to 2	- - KSPBCGSLSetEll()
	-ksp_bcgsl_cxpol	- Use a convex function of the MinRes and OR polynomials after the BiCG step instead of default MinRes -- KSPBCGSLSetPol()
	-ksp_bcgsl_mrpoly	- Use the default MinRes polynomial after the BiCG step -- KSPBCGSLSetPol()
	-ksp_bcgsl_xres <res> Threshold used to decide when to refresh computed residuals	- - KSPBCGSLSetXRes()
	-ksp_bcgsl_pinv <true/false>	- (de)activate use of pseudoinverse -- KSPBCGSLSetUsePseudoinverse()

KSPBCGSL

References

Options Database Keys

See Also