/* nag_dstevd (f08jcc) 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, n, pdz, d_len, e_len;
  Integer       exit_status = 0;
  NagError      fail;
  Nag_JobType   job;
  Nag_OrderType order;
  /* Arrays */
  char          nag_job_arg[40];
  double        *z = 0, *d = 0, *e = 0;
  
#ifdef NAG_COLUMN_MAJOR
#define Z(I, J) z[(J - 1) * pdz + I - 1]
  order = Nag_ColMajor;
#else
#define Z(I, J) z[(I - 1) * pdz + J - 1]
  order = Nag_RowMajor;
#endif
  
  INIT_FAIL(fail);
  
  printf("nag_dstevd (f08jcc) Example Program Results\n\n");
  
  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%ld%*[^\n] ", &n);
  pdz = n;
  d_len = n;
  e_len = n - 1;
  
  /* Allocate memory */
  if (!(z = NAG_ALLOC(n * n, double)) ||
      !(d = NAG_ALLOC(d_len, double)) ||
      !(e = NAG_ALLOC(e_len, double)))
    {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
  /* Read T from data file */
  for (i = 0; i < d_len; ++i)
    scanf("%lf", &d[i]);
  for (i = 0; i < e_len; ++i)
    scanf("%lf", &e[i]);
  /* Read type of job to be performed */
  scanf("%*[^\n] ");
  scanf(" %s%*[^\n] ", nag_job_arg);
  /* nag_enum_name_to_value (x04nac).
   * Converts NAG enum member name to value
   */
  job = (Nag_JobType) nag_enum_name_to_value(nag_job_arg);
  
  /* Calculate all the eigenvalues and eigenvectors of T using using */
  /* nag_dstevd (f08jcc)                                             */
  nag_dstevd(order, job, n, d, e, z, pdz, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dstevd (f08jcc).\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("  %7.4lf", d[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 (d) NAG_FREE(d);
  if (e) NAG_FREE(e);
  if (z) NAG_FREE(z);
  return exit_status;
}