NAME

BSpar_isolve - Solve a symmetric indefinite system of equations using symmlq preconditioned by one of several preconditioners.

INPUT PARAMETERS

A: - a sparse matrix
fact_A: - the incomplete factored version of A, if any (NULL if not exist)
comm_A: - the communication structure for A
B: - a sparse matrix
comm_B: - the communication structure for B
in_rhs: - the rhs
shift: - the shift to multiply B by
pre_option: - the preconditioner to use PRE_ICC: incomplete Cholesky factorization of A PRE_ILU: incomplete LU factorization of A PRE_SSOR: Successive over relaxation (using just A) PRE_BJACOBI: Block Jacobi (using just A)
residual: - the final computed residual
procinfo: - the usual processor stuff

OUTPUT PARAMETERS

out_x: - the solution vector

RETURNS

The number of iterations.

NOTES

The system solved is (A-shift*B)out_x = in_rhs. The preconditioners must be computed prior to calling BSpar_isolve. For more information on the preconditioners, see the manual.

The following are now specified in the context: err_tol - the tolerance to which to solve the problem stop if the estimated norm of the residual divided by the norm of the rhs is less than err_tol max_iter - the maximum number of iterations to take guess - if TRUE, then initialize out_x to 0, otherwise the program assumes that out_x contains an initial guess

SYNOPSIS

int BSpar_isolve(BSpar_mat *A, BSpar_mat *fact_A, BScomm *comm_A,
 BSpar_mat *B, BScomm *comm_B, FLOAT *in_rhs, FLOAT *out_x,
 FLOAT shift, FLOAT *residual, BSprocinfo *procinfo)

LOCATION

BlockSolve95/src/BSpar_isolve.c