/* nag_sparse_direct_real_gen_cond (f11mgc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.2, 2024.
 */

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

int main(void) {
  double anorm, d, flop, rcond, thresh;
  Integer exit_status = 0, i, n, nnz, nnzl, nnzu, nzlmx, nzlumx, nzumx;
  double *a = 0, *lval = 0, *uval = 0;
  Integer *icolzp = 0, *il = 0, *iprm = 0, *irowix = 0;
  Integer *iu = 0;
  /* Nag types */
  NagError fail;
  Nag_ColumnPermutationType ispec;
  Nag_NormType norm;

  INIT_FAIL(fail);

  printf("nag_sparse_direct_real_gen_cond (f11mgc) Example Program "
         "Results\n\n");
  /* Skip heading in data file */
  scanf("%*[^\n] ");
  /* Read order of matrix */
  scanf("%" NAG_IFMT "%*[^\n] ", &n);
  /* Read the matrix A */
  if (!(icolzp = NAG_ALLOC(n + 1, Integer))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }
  for (i = 1; i <= n + 1; ++i)
    scanf("%" NAG_IFMT "%*[^\n] ", &icolzp[i - 1]);
  nnz = icolzp[n] - 1;
  /* Allocate memory */
  if (!(irowix = NAG_ALLOC(nnz, Integer)) || !(a = NAG_ALLOC(nnz, double)) ||
      !(il = NAG_ALLOC(7 * n + 8 * nnz + 4, Integer)) ||
      !(iu = NAG_ALLOC(2 * n + 8 * nnz + 1, Integer)) ||
      !(uval = NAG_ALLOC(8 * nnz, double)) ||
      !(lval = NAG_ALLOC(8 * nnz, double)) ||
      !(iprm = NAG_ALLOC(7 * n, Integer))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }
  for (i = 1; i <= nnz; ++i)
    scanf("%lf%" NAG_IFMT "%*[^\n] ", &a[i - 1], &irowix[i - 1]);

  /* Calculate COLAMD permutation */
  ispec = Nag_Sparse_Colamd;
  /* nag_sparse_direct_real_gen_setup (f11mdc).
   * Real sparse nonsymmetric linear systems, setup for
   * nag_sparse_direct_real_gen_lu (f11mec)
   */
  nag_sparse_direct_real_gen_setup(ispec, n, icolzp, irowix, iprm, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_sparse_direct_real_gen_setup (f11mdc).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

  /* Factorise */
  thresh = 1.;
  nzlmx = 8 * nnz;
  nzlumx = 8 * nnz;
  nzumx = 8 * nnz;
  /* nag_sparse_direct_real_gen_lu (f11mec).
   * LU factorization of real sparse matrix
   */
  nag_sparse_direct_real_gen_lu(n, irowix, a, iprm, thresh, nzlmx, &nzlumx,
                                nzumx, il, lval, iu, uval, &nnzl, &nnzu, &flop,
                                &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_sparse_direct_real_gen_lu (f11mec).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

  /* Calculate norm */
  norm = Nag_RealOneNorm;
  /* nag_sparse_direct_real_gen_norm (f11mlc).
   * 1-norm, infinity-norm, largest absolute element, real
   * general matrix
   */
  nag_sparse_direct_real_gen_norm(norm, &anorm, n, icolzp, irowix, a, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_sparse_direct_real_gen_norm (f11mlc).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

  /* Calculate condition number */
  /* nag_sparse_direct_real_gen_cond (f11mgc).
   * Estimate condition number of real matrix, matrix already
   * factorized by nag_sparse_direct_real_gen_lu (f11mec)
   */
  nag_sparse_direct_real_gen_cond(norm, n, il, lval, iu, uval, anorm, &rcond,
                                  &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_sparse_direct_real_gen_cond (f11mgc).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

  /* Output result */
  d = 1 / rcond;
  printf("\n   Norm,  Condition number\n %7.3f,%7.3f\n\n", anorm, d);

END:
  NAG_FREE(a);
  NAG_FREE(lval);
  NAG_FREE(uval);
  NAG_FREE(icolzp);
  NAG_FREE(il);
  NAG_FREE(iprm);
  NAG_FREE(irowix);
  NAG_FREE(iu);

  return exit_status;
}