NAME

BSpar_sym_solve - Solve a symmetric positive definite system of equations using conjugate gradients preconditioned by one of several preconditioners. The rhs can be a block of vectors. The user should not call this function directly, but BSpar_solve().

INPUT PARAMETERS

BS: - the number of vectors in the RHS
A: - a sparse matrix
fact_A: - the incomplete factored version of A, if any
comm_A: - the communication structure for A
in_rhs: - the contiguous block of vectors forming the rhs
pre_option: - the preconditioner to use PRE_ICC: incomplete Cholesky factorization PRE_ILU: incomplete LU factorization PRE_SSOR: Successive over relaxation PRE_BJACOBI: Block Jacobi
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
residual: - the final computed residual
guess: - if TRUE, then initialize out_x to 0, otherwise the program assumes that out_x contains an initial guess
procinfo: - the usual processor stuff

OUTPUT PARAMETERS

out_x: - the contiguous block of vectors containing the solution

RETURNS

The number of iterations or a negative number indicating the number of iterations prior to finding that the matrix (or preconditioner) is not positive definite.

NOTES

The preconditioners must be computed prior to calling BSpar_isolve. For more information on the preconditioners, see the manual.

SYNOPSIS

int BSpar_sym_solve(int BS, BSpar_mat *A, BSpar_mat *fact_A, BScomm *comm_A,
 FLOAT *in_rhs, FLOAT *out_x, int pre_option, FLOAT err_tol, int max_iter,
 FLOAT *residual, int guess, BSprocinfo *procinfo)

LOCATION

BlockSolve95/src/BSpar_sym_solve.c