/* nag_sparse_sym_chol_sol (f11jcc) Example Program.
 *
 * Copyright 1998 Numerical Algorithms Group.
 *
 * Mark 5, 1998.
 *
 */

#include <nag.h>
#include <nagx04.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nag_string.h>
#include <nagf11.h>

int main(int argc, char *argv[])
{
  FILE                 *fpin, *fpout;
  double               dtol;
  double               *a = 0, *b = 0;
  double               *x = 0;
  double               rnorm, dscale;
  double               tol;
  Integer              exit_status = 0;
  Integer              *icol = 0;
  Integer              *ipiv = 0, nnzc, *irow = 0, *istr = 0;
  Integer              i;
  Integer              n;
  Integer              lfill, npivm;
  Integer              maxitn;
  Integer              itn;
  Integer              nnz;
  Integer              num;
  char                 nag_enum_arg[40];
  Nag_SparseSym_Method method;
  Nag_SparseSym_Piv    pstrat;
  Nag_SparseSym_Fact   mic;
  Nag_Sparse_Comm      comm;
  NagError             fail;

  INIT_FAIL(fail);

  /* Check for command-line IO options */
  fpin = nag_example_file_io(argc, argv, "-data", NULL);
  fpout = nag_example_file_io(argc, argv, "-results", NULL);

  fprintf(fpout, "nag_sparse_sym_chol_sol (f11jcc) Example Program Results\n");

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

  /* Read algorithmic parameters */
  fscanf(fpin, "%ld%*[^\n]", &n);
  fscanf(fpin, "%ld%*[^\n]", &nnz);
  fscanf(fpin, "%ld%lf%*[^\n]", &lfill, &dtol);
  fscanf(fpin, "%s%*[^\n]", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  method = (Nag_SparseSym_Method) nag_enum_name_to_value(nag_enum_arg);
  fscanf(fpin, "%s%lf%*[^\n]", nag_enum_arg, &dscale);
  mic = (Nag_SparseSym_Fact) nag_enum_name_to_value(nag_enum_arg);
  fscanf(fpin, "%s%*[^\n]", nag_enum_arg);
  pstrat = (Nag_SparseSym_Piv) nag_enum_name_to_value(nag_enum_arg);

  fscanf(fpin, "%lf%ld%*[^\n]", &tol, &maxitn);

  /* Read the matrix a */

  num = 2 * nnz;
  irow = NAG_ALLOC(num, Integer);
  icol = NAG_ALLOC(num, Integer);
  a = NAG_ALLOC(num, double);
  b = NAG_ALLOC(n, double);
  x = NAG_ALLOC(n, double);
  istr = NAG_ALLOC(n+1, Integer);
  ipiv = NAG_ALLOC(num, Integer);

  if (!irow || !icol || !a || !x || !istr || !ipiv)
    {
      fprintf(fpout, "Allocation failure\n");
      return EXIT_FAILURE;
    }

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

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

  /* Calculate incomplete Cholesky factorization */

  /* nag_sparse_sym_chol_fac (f11jac).
   * Incomplete Cholesky factorization (symmetric)
   */
  nag_sparse_sym_chol_fac(n, nnz, &a, &num, &irow, &icol, lfill, dtol, mic,
                          dscale, pstrat, ipiv, istr, &nnzc, &npivm, &comm,
                          &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_sparse_sym_chol_fac (f11jac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

  /* Solve Ax = b */

  /* nag_sparse_sym_chol_sol (f11jcc).
   * Solver with incomplete Cholesky preconditioning
   * (symmetric)
   */
  nag_sparse_sym_chol_sol(method, n, nnz, a, num, irow, icol, ipiv, istr, b,
                          tol, maxitn, x, &rnorm, &itn, &comm, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_sparse_sym_chol_sol (f11jcc).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

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

  /* Output x */

  for (i = 1; i <= n; ++i)
    fprintf(fpout, " %16.4e\n", x[i-1]);

 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (irow) NAG_FREE(irow);
  if (icol) NAG_FREE(icol);
  if (a) NAG_FREE(a);
  if (b) NAG_FREE(b);
  if (x) NAG_FREE(x);
  if (ipiv) NAG_FREE(ipiv);
  if (istr) NAG_FREE(istr);

  return exit_status;
}