/* nag_dsbevd (f08hcc) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf08.h>
#include <nagx04.h>

int main(void)
{
  /* Scalars */
  Integer       i, j, k, kd, n, pdab, pdz, w_len;
  Integer       exit_status = 0;
  NagError      fail;
  Nag_JobType   job;
  Nag_UploType  uplo;
  Nag_OrderType order;
  /* Arrays */
  char          nag_enum_arg[40];
  double        *ab = 0, *w = 0, *z = 0;

#ifdef NAG_COLUMN_MAJOR
#define AB_UPPER(I, J) ab[(J - 1) * pdab + k + I - J - 1]
#define AB_LOWER(I, J) ab[(J - 1) * pdab + I - J]
#define Z(I, J) z[(J - 1) * pdz + I - 1]
  order = Nag_ColMajor;
#else
#define AB_UPPER(I, J) ab[(I - 1) * pdab + J - I]
#define AB_LOWER(I, J) ab[(I - 1) * pdab + k + J - I - 1]
#define Z(I, J) z[(I - 1) * pdz + J - 1]
  order = Nag_RowMajor;
#endif
  
  INIT_FAIL(fail);
  
  printf("nag_dsbevd (f08hcc) Example Program Results\n\n");
  
  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%ld%ld%*[^\n] ", &n, &kd);
  pdab = kd + 1;
  pdz = n;
  w_len = n;
  
  /* Allocate memory */
  if (!(ab = NAG_ALLOC(pdab * n, double)) ||
      !(w = NAG_ALLOC(w_len, double)) ||
      !(z = NAG_ALLOC(n * n, double)))
    {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
  /* Read whether Upper or Lower part of A is stored */
  scanf("%s%*[^\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);
  /* Read A from data file */
  k = kd + 1;
  if (uplo == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= MIN(i + kd, n); ++j)
            scanf("%lf", &AB_UPPER(i, j));
        }
      scanf("%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = MAX(1, i - kd); j <= i; ++j)
            scanf("%lf", &AB_LOWER(i, j));
        }
      scanf("%*[^\n] ");
    }
  /* Read type of job to be performed */
  scanf("%s%*[^\n] ", nag_enum_arg);
  job = (Nag_JobType) nag_enum_name_to_value(nag_enum_arg);
  /* Calculate all the eigenvalues and eigenvectors of A */
  /* nag_dsbevd (f08hcc).
   * All eigenvalues and optionally all eigenvectors of real
   * symmetric band matrix (divide-and-conquer)
   */
  nag_dsbevd(order, job, uplo, n, kd, ab, pdab, w, z, pdz, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dsbevd (f08hcc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Normalize the eigenvectors */
  for(j=1; j<=n; j++)
    {
      for(i=n; i>=1; i--)
        {
          Z(i, j) = Z(i, j) / Z(1,j);
        }
    }
  /* Print eigenvalues and eigenvectors */
  printf(" Eigenvalues\n");
  for (i = 0; i < n; ++i)
    printf(" %8.4lf", w[i]);
  printf("\n\n");
  /* nag_gen_real_mat_print (x04cac).
   * Print real general matrix (easy-to-use)
   */
  fflush(stdout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
                         z, pdz, "Eigenvectors", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
             fail.message);
      exit_status = 1;
      goto END;
    }
 END:
  if (ab) NAG_FREE(ab);
  if (w) NAG_FREE(w);
  if (z) NAG_FREE(z);
  return exit_status;
}