.TH BSpar_solve 3 "1/10/1996" " " "BlockSolve95"
.SH NAME
BSpar_solve \- General solver of a system of equations preconditioned
by one of several preconditioners and using one of several
possible methods.  The rhs can be a block of vectors.

.SH INPUT PARAMETERS
.PD 0
.TP
.B A 
- a sparse matrix
.PD 1
.PD 0
.TP
.B fact_A 
- the incomplete factored version of A, if any
.PD 1
.PD 0
.TP
.B comm_A 
- the communication structure for A
.PD 1
.PD 0
.TP
.B rhs 
- the contiguous block of vectors forming the rhs
.PD 1
.PD 0
.TP
.B residual 
- the final computed residual
.PD 1

.SH OUTPUT PARAMETERS
.PD 0
.TP
.B x 
- the contiguous block of vectors containing the solution (can
contain an initial guess if BSctx_set_guess() is set.
.PD 1

.SH NOW SPECIFIED IN PROCINFO CONTEXT
.PD 0
.TP
.B pre_option 
- the preconditioner to use:
.PD 1
.br
          PRE_ICC: incomplete Cholesky factorization
.br
          PRE_ILU: incomplete LU factorization
.br
          PRE_SSOR: Successive over relaxation
.br
          PRE_BJACOBI: Block Jacobi
.PD 0
.TP
.B 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
.PD 1
.PD 0
.TP
.B max_iter 
- the maximum number of iterations to take
.PD 1
.PD 0
.TP
.B guess 
- if TRUE, then initialize out_x to 0, otherwise the program
assumes that out_x contains an initial guess
.PD 1
.PD 0
.TP
.B procinfo 
- the usual processor stuff
.PD 1

.SH 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.

.SH NOTES
The preconditioners must be computed prior to calling BSpar_solve.
For more information on the preconditioners, see the manual or
BSctx_set_pre().

.SH SYNOPSIS
.nf
int BSpar_solve(BSpar_mat *A, BSpar_mat *fact_A, BScomm *comm_A,
 FLOAT *rhs, FLOAT *x, FLOAT *residual, BSprocinfo *procinfo)

.fi

.SH LOCATION
 BlockSolve95/src/BSpar_solve.c