/* nag_sparse_nsym_sol (f11dec) Example Program.
 *
 * Copyright 1998 Numerical Algorithms Group.
 *
 * Mark 5, 1998.
 */

#include <nag.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nag_string.h>
#include <nagf11.h>

int main(void)
{
  double  *a=0, *b=0, *x=0;
  double omega;
  double rnorm;
  double tol;

  Integer *icol=0, *irow=0;
  Integer i, m, n;
  Integer maxitn, itn;
  Integer nnz;

  Nag_SparseNsym_Method method;
  Nag_SparseNsym_PrecType precon;
  Nag_Sparse_Comm comm;
  char char_enum[20];

  Vprintf("nag_sparse_nsym_sol (f11dec) Example Program Results\n");
  /* Skip heading in data file */
  Vscanf("%*[^\n]");
  Vscanf("%ld%*[^\n]",&n);
  Vscanf("%ld%*[^\n]",&nnz);

  Vscanf("%s",char_enum);
  if (!strcmp(char_enum, "RGMRES"))
    method = Nag_SparseNsym_RGMRES;
  else if (!strcmp(char_enum, "CGS"))
    method = Nag_SparseNsym_CGS;
  else if (!strcmp(char_enum, "BiCGSTAB"))
    method = Nag_SparseNsym_BiCGSTAB;
  else
    {
      Vprintf("Unrecognised string for method enum representation.\n");
      return EXIT_FAILURE;
    }

  Vscanf("%s%*[^\n]",char_enum);
  if (!strcmp(char_enum, "NoPrec"))
    precon = Nag_SparseNsym_NoPrec;
  else if (!strcmp(char_enum, "SSORPrec"))
    precon = Nag_SparseNsym_SSORPrec;
  else if (!strcmp(char_enum, "JacPrec"))
    precon = Nag_SparseNsym_JacPrec;
  else
    {
      Vprintf("Unrecognised string for precon enum representation.\n");
      return EXIT_FAILURE;
    }

  Vscanf("%lf%*[^\n]",&omega);
  Vscanf("%ld%lf%ld%*[^\n]",&m,&tol,&maxitn);

  x = NAG_ALLOC(n,double);
  b = NAG_ALLOC(n,double);
  a = NAG_ALLOC(nnz,double);
  irow = NAG_ALLOC(nnz,Integer);
  icol = NAG_ALLOC(nnz,Integer);
  if (!irow || !icol || !a || !x || !b)
    {
      Vprintf("Allocation failure\n");
      return EXIT_FAILURE;
    }



  /* Read the matrix a */

  for (i = 1; i <= nnz; ++i)
    Vscanf("%lf%ld%ld%*[^\n]",&a[i-1], &irow[i-1],
           &icol[i-1] );

  /* Read right-hand side vector b and initial approximate solution x */

  for (i = 1; i <= n; ++i)
    Vscanf("%lf",&b[i-1]);
  Vscanf("%*[^\n]");

  for (i = 1; i <= n; ++i)
    Vscanf("%lf",&x[i-1]);
  Vscanf("%*[^\n]");

  /* Solve Ax = b using nag_sparse_nsym_sol (f11dec) */

  /* nag_sparse_nsym_sol (f11dec).
   * Solver with no Jacobi/SSOR preconditioning (nonsymmetric)
   */
  nag_sparse_nsym_sol(method, precon, n, nnz, a, irow, icol, omega, b, m, tol,
                      maxitn, x, &rnorm, &itn, &comm, NAGERR_DEFAULT);

  Vprintf("%s%10ld%s\n","Converged in",itn," iterations");
  Vprintf("%s%16.3e\n","Final residual norm =",rnorm);

  /* Output x */
  Vprintf("           x\n");
  for (i = 1; i <= n; ++i)
    Vprintf(" %16.6e\n",x[i-1]);

  NAG_FREE(irow);
  NAG_FREE(icol);
  NAG_FREE(a);
  NAG_FREE(x);
  NAG_FREE(b);
  return EXIT_SUCCESS;
}