/* nag_sparse_nsym_precon_ssor_solve (f11ddc) Example Program.
 *
 * Copyright 2011, Numerical Algorithms Group.
 *
 * Mark 23, 2011.
 */
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf11.h>
int main(void)
{
  /* Scalars */
  Integer                     exit_status = 0;
  double                      anorm, omega, sigmax, stplhs, stprhs, tol;
  Integer                     i, irevcm, iterm, itn, la, liwork,
                              lwneed, lwork, m, maxitn, monit, n, nnz;
  /* Arrays */
  char                        nag_enum_arg[100];
  double                      *a = 0, *b = 0, *rdiag = 0, *wgt = 0,
                              *work = 0, *x = 0;
  Integer                     *icol = 0, *irow = 0, *iwork = 0;
  /* NAG types */
  Nag_SparseNsym_CheckData    ckdd,ckxa;
  Nag_NormType                norm;
  Nag_SparseNsym_PrecType     precon;
  Nag_TransType               trans;
  Nag_SparseNsym_Weight       weight;
  Nag_SparseNsym_Method       method;
  NagError                    fail, fail1;

  INIT_FAIL(fail);
  INIT_FAIL(fail1);

  printf("nag_sparse_nsym_precon_ssor_solve (f11ddc) Example Program Results");
  printf("\n\n");
  /* Skip heading in data file*/
  scanf("%*[^\n]");
  /* Read algorithmic parameters*/
  scanf("%ld%ld%*[^\n]", &n, &m);
  scanf("%ld%*[^\n]", &nnz);
  la = 3 * nnz;
  lwork = MAX(n * (m + 3) + m * (m + 5) + 101, 7 * n + 100);
  liwork = 2 * n + 1;
  if (
    !(a = NAG_ALLOC((la), double)) ||
    !(b = NAG_ALLOC((n), double)) ||
    !(rdiag = NAG_ALLOC((n), double)) ||
    !(wgt = NAG_ALLOC((n), double)) ||
    !(work = NAG_ALLOC((lwork), double)) ||
    !(x = NAG_ALLOC((n), double)) ||
    !(icol = NAG_ALLOC((la), Integer)) ||
    !(irow = NAG_ALLOC((la), Integer)) ||
    !(iwork = NAG_ALLOC((liwork), Integer))
    )
    {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
  /* Read or initialize the parameters for the iterative solver*/
  scanf("%s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  method = (Nag_SparseNsym_Method) nag_enum_name_to_value(nag_enum_arg);

  scanf("%s%*[^\n]", nag_enum_arg);
  precon = (Nag_SparseNsym_PrecType) nag_enum_name_to_value(nag_enum_arg);

  scanf("%s%*[^\n]", nag_enum_arg);
  norm = (Nag_NormType) nag_enum_name_to_value(nag_enum_arg);

  scanf("%ld%*[^\n]", &iterm);
  scanf("%lf%ld%*[^\n]", &tol, &maxitn);
  scanf("%lf%lf%*[^\n]", &anorm, &sigmax);
  scanf("%lf%*[^\n]", &omega);

  /* Read the non-zero elements of the matrix a*/
  for (i = 0; i < nnz; i++)
    scanf("%lf%ld%ld%*[^\n] ", &a[i], &irow[i], &icol[i]);

  /* Read right-hand side vector b and initial approximate solution x*/
  for (i = 0; i < n; i++)  scanf("%lf", &b[i]);
  scanf("%*[^\n]");
  for (i = 0; i < n; i++)  scanf("%lf", &x[i]);

  weight = Nag_SparseNsym_UnWeighted;
  monit = 0;
  /* Call to initialize the solver
   * nag_sparse_nsym_basic_setup (f11bdc)
   * Real sparse nonsymmetric linear systems, setup routine
   */
  nag_sparse_nsym_basic_setup(method, precon, norm, weight, iterm, n, m, tol,
			      maxitn, anorm, sigmax, monit, &lwneed, work,
			      lwork, &fail);
  /* Calculate reciprocal diagonal matrix elements if necessary*/
  if (precon == Nag_SparseNsym_Prec) {
    for (i = 0; i < n; i++)  iwork[i] = 0;
    for (i = 0; i < nnz; i++) {
      if (irow[i] == icol[i]) {
	iwork[irow[i]-1]++;
	if (a[i] == 0.0) {
	  printf("Matrix has a zero diagonal element \n");
	  goto END;
	}
	rdiag[(irow[i]-1)] = 1.0/a[i];
      }
    }
    for (i = 0; i < n; i++) {
      if (iwork[i] == 0) {
	printf("Matrix has a missing diagonal element \n");
	goto END;
      }
      if (iwork[i] >= 2) {
	printf("Matrix has a multiple diagonal element \n");
	goto END;
      }
    }
  }
  /* call solver repeatedly to solve the equations*/
  irevcm = 0;
  ckxa = Nag_SparseNsym_Check;
  ckdd = Nag_SparseNsym_Check;
  while (irevcm!=4)
    {
      /* nag_sparse_nsym_basic_solver (f11bec)
       * Real sparse nonsymmetric linear systems, solver routine
       * preconditioned RGMRES, CGS, Bi-CGSTAB or TFQMR method
       */
      nag_sparse_nsym_basic_solver(&irevcm, x, b, wgt, work, lwork, &fail);
      switch (irevcm) {
      case 1:
        /* Compute matrix-vector product using
         * nag_sparse_nsym_matvec (f11xac)
         * Real sparse nonsymmetric matrix vector multiply
         */
	trans = Nag_NoTrans;
	nag_sparse_nsym_matvec(trans, n, nnz, a, irow, icol, ckxa, x, b,
			       &fail1);
	ckxa = Nag_SparseNsym_NoCheck;
	break;
      case -1:
        /* Compute transposed matrix-vector product */
	trans = Nag_Trans;
	nag_sparse_nsym_matvec(trans, n, nnz, a, irow, icol, ckxa, x, b,
			       &fail1);
	ckxa = Nag_SparseNsym_NoCheck;
	break;
      case 2:
        /* SSOR preconditioning using 
         * nag_sparse_nsym_precon_ssor_solve (f11ddc)
         * Solution of linear system involving preconditioning matrix generated
         * by applying SSOR to real sparse nonsymmetric matrix
         */
	trans = Nag_NoTrans;
	nag_sparse_nsym_precon_ssor_solve(trans, n, nnz, a, irow, icol, rdiag,
					  omega, ckdd, x, b,&fail1);
	ckdd = Nag_SparseNsym_NoCheck;
	break;
      }
      if (fail1.code != NE_NOERROR) irevcm = 6;
    }
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_sparse_nsym_basic_solver (f11bec)\n%s\n",
	     fail.message);
      exit_status = 1;
      goto END;
    }

  /* nag_sparse_nsym_basic_diagnostic (f11bfc)
   * Real sparse nonsymmetric linear systems, diagnostic
   */
  nag_sparse_nsym_basic_diagnostic(&itn, &stplhs, &stprhs, &anorm, &sigmax,
				   work, lwork, &fail);
  printf(" Converged in %11ld iterations\n", itn);
  printf(" Matrix norm         = %9.3e\n", anorm);
  printf(" Final residual norm = %9.3e\n\n", stplhs);
  /* Output x*/
  printf(" Solution of linear system\n");
  for (i = 0; i < n; i++)  printf("%16.4e\n", x[i]);

 END:
  if (a) NAG_FREE(a);
  if (b) NAG_FREE(b);
  if (rdiag) NAG_FREE(rdiag);
  if (wgt) NAG_FREE(wgt);
  if (work) NAG_FREE(work);
  if (x) NAG_FREE(x);
  if (icol) NAG_FREE(icol);
  if (irow) NAG_FREE(irow);
  if (iwork) NAG_FREE(iwork);
  return exit_status;
}