/* nag_lapacklin_dpbequ (f07hfc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.3, 2024.
 */

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

int main(void) {

  /* Scalars */
  double amax, big, scond, small;
  Integer exit_status = 0, i, j, kd, kd1, kd2, n, pdab;

  /* Arrays */
  double *ab = 0, *s = 0;
  char nag_enum_arg[40];

  /* Nag Types */
  NagError fail;
  Nag_UploType uplo;
  Nag_OrderType order;

#ifdef NAG_COLUMN_MAJOR
#define AB_UPPER(I, J) ab[(J - 1) * pdab + kd + I - J]
#define AB_LOWER(I, J) ab[(J - 1) * pdab + I - J]
  order = Nag_ColMajor;
#else
#define AB_UPPER(I, J) ab[(I - 1) * pdab + J - I]
#define AB_LOWER(I, J) ab[(I - 1) * pdab + kd + J - I]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);

  printf("nag_lapacklin_dpbequ (f07hfc) Example Program Results\n\n");
  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n]", &n, &kd);
  if (n < 0 || kd < 0) {
    printf("Invalid n or kd\n");
    exit_status = 1;
    goto END;
  }
  scanf(" %39s%*[^\n]", nag_enum_arg);
  /* nag_enum_name_to_value (x04nac).
   * Converts NAG enum member name to value
   */
  uplo = (Nag_UploType)nag_enum_name_to_value(nag_enum_arg);

  pdab = kd + 1;
  /* Allocate memory */
  if (!(ab = NAG_ALLOC((kd + 1) * n, double)) || !(s = NAG_ALLOC(n, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  /* Read the upper or lower triangular part of the band matrix A
   * from data file.
   */
  if (uplo == Nag_Upper) {
    kd1 = 0;
    kd2 = kd;
    for (i = 1; i <= n; ++i)
      for (j = i; j <= MIN(n, i + kd); ++j)
        scanf("%lf", &AB_UPPER(i, j));
  } else {
    kd1 = kd;
    kd2 = 0;
    for (i = 1; i <= n; ++i)
      for (j = MAX(1, i - kd); j <= i; ++j)
        scanf("%lf", &AB_LOWER(i, j));
  }
  scanf("%*[^\n]");

  /* Print the matrix A using nag_file_print_matrix_real_band (x04cec). */

  fflush(stdout);
  nag_file_print_matrix_real_band(order, n, n, kd1, kd2, ab, pdab, "Matrix A",
                                  0, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_file_print_matrix_real_band (x04cec).\n%s\n",
           fail.message);
    exit_status = 2;
    goto END;
  }
  printf("\n");

  /* Compute diagonal scaling factors using nag_lapacklin_dpbequ (f07hfc). */
  nag_lapacklin_dpbequ(order, uplo, n, kd, ab, pdab, s, &scond, &amax, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_dpbequ (f07hfc).\n%s\n", fail.message);
    exit_status = 3;
    goto END;
  }
  /* Print scond, amax and the scale factors */
  printf("scond = %10.1e, amax = %10.1e\n", scond, amax);
  printf("\nDiagonal scaling factors\n");
  for (i = 0; i < n; ++i)
    printf("%11.1e%s", s[i], i % 7 == 6 ? "\n" : " ");
  printf("\n\n");

  /* Compute values close to underflow and overflow using
   * nag_machine_real_safe (x02amc), nag_machine_precision (x02ajc) and
   * nag_machine_model_base (x02bhc)
   */
  small =
      nag_machine_real_safe / (nag_machine_precision * nag_machine_model_base);
  big = 1.0 / small;
  if (scond < 0.1 || amax < small || amax > big) {
    /* Scale A */
    if (uplo == Nag_Upper)
      for (j = 1; j <= n; ++j)
        for (i = MAX(1, j - kd); i <= j; ++i)
          AB_UPPER(i, j) *= s[i - 1] * s[j - 1];
    else
      for (j = 1; j <= n; ++j)
        for (i = j; i <= MIN(n, j + kd); ++i)
          AB_LOWER(i, j) *= s[i - 1] * s[j - 1];

    /* Print the scaled matrix using nag_file_print_matrix_real_band (x04cec).
     */
    fflush(stdout);
    nag_file_print_matrix_real_band(order, n, n, kd1, kd2, ab, pdab,
                                    "Scaled matrix", 0, &fail);
    if (fail.code != NE_NOERROR) {
      printf("Error from nag_file_print_matrix_real_band (x04cec).\n%s\n",
             fail.message);
      exit_status = 4;
      goto END;
    }
  }
END:
  NAG_FREE(ab);
  NAG_FREE(s);

  return exit_status;
}

#undef AB_UPPER
#undef AB_LOWER