/* nag_sparse_sym_sol (f11jec) 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>

/* f11jec Example Program Text */

int main(void)

{
  double *a=0, *b=0, *x=0;
  double omega;
  double rnorm;
  double tol;

  Integer *icol, *irow;
  Integer i, n, maxitn, itn, nnz;

  Nag_SparseSym_Method method;
  Nag_SparseSym_PrecType precon;
  Nag_Sparse_Comm comm;

  char char_enum[20];

  Vprintf("f11jec Example Program Results\n");

  /* Skip heading in data file  */
  Vscanf(" %*[^\n]");

  /* Read algorithmic parameters */
  Vscanf("%ld%*[^\n]",&n);
  Vscanf("%ld%*[^\n]",&nnz);

  Vscanf("%s",char_enum);
  if (!strcmp(char_enum, "CG"))
    method = Nag_SparseSym_CG;
  else if (!strcmp(char_enum, "Lanczos"))
    method = Nag_SparseSym_Lanczos;
  else
    {
      Vprintf("Unrecognised string for method enum representation.\n");
      return EXIT_FAILURE;
    }

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

  Vscanf("%lf%*[^\n]",&omega);
  Vscanf("%lf%ld%*[^\n]",&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  */
  f11jec(method, precon, n, nnz, a, irow, icol, omega, b, 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 */
  for (i = 1; i <= n; ++i)
    Vprintf(" %16.4e\n",x[i-1]);
  NAG_FREE(irow);
  NAG_FREE(icol);
  NAG_FREE(a);
  NAG_FREE(x);
  NAG_FREE(b);
  return EXIT_SUCCESS;
}