/* nag_sparse_nsym_fac_solve (f11dcc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.3, 2024.
 *
 */

#include <nag.h>
#include <stdio.h>

int main(void) {
  double dtol;
  double *a = 0, *b = 0;
  double *x = 0;
  double rnorm;
  double tol;
  Integer exit_status = 0;
  Integer *irow, *icol;
  Integer *istr = 0, *idiag, *ipivp = 0, *ipivq = 0;
  Integer i, m, n, nnzc;
  Integer lfill, npivm;
  Integer maxitn;
  Integer itn;
  Integer nnz;
  Integer num;
  char nag_enum_arg[40];
  Nag_SparseNsym_Method method;
  Nag_SparseNsym_Piv pstrat;
  Nag_SparseNsym_Fact milu;
  Nag_Sparse_Comm comm;
  NagError fail;

  INIT_FAIL(fail);

  printf("nag_sparse_real_gen_solve_ilu (f11dcc) Example Program Results\n");

  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%" NAG_IFMT "%*[^\n]", &n);
  scanf("%" NAG_IFMT "%*[^\n]", &nnz);
  scanf("%39s%*[^\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("%" NAG_IFMT "%lf%*[^\n]", &lfill, &dtol);
  scanf("%39s%*[^\n]", nag_enum_arg);
  pstrat = (Nag_SparseNsym_Piv)nag_enum_name_to_value(nag_enum_arg);
  scanf("%39s%*[^\n]", nag_enum_arg);
  milu = (Nag_SparseNsym_Fact)nag_enum_name_to_value(nag_enum_arg);
  scanf("%" NAG_IFMT "%lf%" NAG_IFMT "%*[^\n]", &m, &tol, &maxitn);

  /* Read the matrix a */

  num = 2 * nnz;
  istr = NAG_ALLOC(n + 1, Integer);
  idiag = NAG_ALLOC(n, Integer);
  ipivp = NAG_ALLOC(n, Integer);
  ipivq = NAG_ALLOC(n, Integer);
  x = NAG_ALLOC(n, double);
  b = NAG_ALLOC(n, double);
  a = NAG_ALLOC(num, double);
  irow = NAG_ALLOC(num, Integer);
  icol = NAG_ALLOC(num, Integer);
  if (!istr || !idiag || !ipivp || !ipivq || !irow || !icol || !a || !x || !b) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

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

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

  /* Calculate incomplete LU factorization */

  /* nag_sparse_real_gen_precon_ilu (f11dac).
   * Incomplete LU factorization (nonsymmetric)
   */
  nag_sparse_real_gen_precon_ilu(n, nnz, &a, &num, &irow, &icol, lfill, dtol,
                                 pstrat, milu, ipivp, ipivq, istr, idiag, &nnzc,
                                 &npivm, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_sparse_real_gen_precon_ilu (f11dac).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

  /* nag_sparse_real_gen_solve_ilu (f11dcc).
   * Solver with incomplete LU preconditioning (nonsymmetric)
   */
  /* Solve Ax = b using nag_sparse_real_gen_solve_ilu (f11dcc) */
  nag_sparse_real_gen_solve_ilu(method, n, nnz, a, num, irow, icol, ipivp,
                                ipivq, istr, idiag, b, m, tol, maxitn, x,
                                &rnorm, &itn, &comm, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_sparse_real_gen_solve_ilu (f11dcc).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

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

  /* Output x */

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

END:
  NAG_FREE(istr);
  NAG_FREE(idiag);
  NAG_FREE(ipivp);
  NAG_FREE(ipivq);
  NAG_FREE(irow);
  NAG_FREE(icol);
  NAG_FREE(a);
  NAG_FREE(x);
  NAG_FREE(b);

  return exit_status;
}