/* nag_sparse_complex_herm_precon_ilu_solve (f11jpc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.1, 2024.
 */

#include <nag.h>

int main(void) {
  /* Scalars */
  Integer exit_status = 0;
  double dscale, dtol;
  Integer i, la, lfill, n, nnz, nnzc, npivm;
  /* Arrays */
  Complex *a = 0, *x = 0, *y = 0;
  Integer *icol = 0, *ipiv = 0, *irow = 0, *istr = 0;
  /* NAG types */
  Nag_SparseSym_Fact mic;
  Nag_SparseSym_Piv pstrat;
  Nag_SparseSym_CheckData check;
  NagError fail;

  INIT_FAIL(fail);

  printf(
      "nag_sparse_complex_herm_precon_ilu_solve (f11jpc) Example Program Results");
  printf("\n\n");
  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%" NAG_IFMT "%*[^\n]", &n);
  scanf("%" NAG_IFMT "%*[^\n]", &nnz);

  /* Allocate memory */
  la = 3 * nnz;
  if (!(a = NAG_ALLOC(la, Complex)) || !(x = NAG_ALLOC(n, Complex)) ||
      !(y = NAG_ALLOC(n, Complex)) || !(icol = NAG_ALLOC(la, Integer)) ||
      !(ipiv = NAG_ALLOC(n, Integer)) || !(irow = NAG_ALLOC(la, Integer)) ||
      !(istr = NAG_ALLOC(n + 1, Integer))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }
  /* Read the matrix a */
  for (i = 0; i <= nnz - 1; i++)
    scanf(" ( %lf , %lf ) %" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &a[i].re,
          &a[i].im, &irow[i], &icol[i]);
  /* Read the vector y */
  for (i = 0; i <= n - 1; i++)
    scanf(" ( %lf , %lf ) ", &y[i].re, &y[i].im);

  lfill = -1;
  dtol = 0.0;
  dscale = 0.0;
  mic = Nag_SparseSym_UnModFact;
  pstrat = Nag_SparseSym_MarkPiv;
  /* Calculate Cholesky factorization using nag_sparse_complex_herm_precon_ichol
   * (f11jnc).
   */
  nag_sparse_complex_herm_precon_ichol(n, nnz, a, la, irow, icol, lfill, dtol,
                                       mic, dscale, pstrat, ipiv, istr, &nnzc,
                                       &npivm, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_sparse_complex_herm_precon_ichol (f11jnc).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }
  /* Check the output value of npivm */
  if (npivm != 0)
    printf("Factorization is not complete \n");
  else {
    /* Solve complex linear system involving incomplete Cholesky factorization
     *
     *              H T
     *       P L D L P x = y
     *
     * using nag_sparse_complex_herm_precon_ilu_solve (f11jpc).
     */
    check = Nag_SparseSym_Check;
    nag_sparse_complex_herm_precon_ilu_solve(n, a, la, irow, icol, ipiv, istr,
                                             check, y, x, &fail);
    if (fail.code != NE_NOERROR) {
      printf(
          "Error from nag_sparse_complex_herm_precon_ilu_solve (f11jpc).\n%s\n",
          fail.message);
      exit_status = 2;
      goto END;
    }
    /* Output results */
    printf("Solution of linear system \n");
    for (i = 0; i <= n - 1; i++)
      printf(" (%13.4e, %13.4e) \n", x[i].re, x[i].im);
  }

END:
  NAG_FREE(a);
  NAG_FREE(x);
  NAG_FREE(y);
  NAG_FREE(icol);
  NAG_FREE(ipiv);
  NAG_FREE(irow);
  NAG_FREE(istr);
  return exit_status;
}