/* nag_dspevd (f08gcc) 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, ap_len, pdz, w_len;
  Integer  exit_status=0;
  NagError fail;
  Nag_JobType    job;
  Nag_UploType   uplo;
  Nag_OrderType  order;
  /* Arrays */
  char   uplo_char[2], job_char[2];
  double *ap=0, *w=0, *z=0;

#ifdef NAG_COLUMN_MAJOR
#define A_UPPER(I,J) ap[J*(J-1)/2 + I - 1]
#define A_LOWER(I,J) ap[(2*n-J)*(J-1)/2 + I - 1]
  order = Nag_ColMajor;
#else
#define A_LOWER(I,J) ap[I*(I-1)/2 + J - 1]
#define A_UPPER(I,J) ap[(2*n-I)*(I-1)/2 + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);
  Vprintf("nag_dspevd (f08gcc) Example Program Results\n\n");

  /* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%ld%*[^\n] ", &n);
  ap_len = n*(n+1)/2;
  w_len = n;
  pdz =n;

  /* Allocate memory */
  if ( !(ap = NAG_ALLOC(ap_len, double)) ||
       !(z = NAG_ALLOC(n * n, double)) ||
       !(w = NAG_ALLOC(w_len, double)) )
    {
      Vprintf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
  /* Read whether Upper or Lower part of A is stored */
  Vscanf(" ' %1s '%*[^\n] ", uplo_char);
  if (*(unsigned char *)uplo_char == 'L')
    uplo = Nag_Lower;
  else if (*(unsigned char *)uplo_char == 'U')
    uplo = Nag_Upper;
  else
    {
      Vprintf("Unrecognised character for Nag_UploType type\n");
      exit_status = -1;
      goto END;
    }
  /* Read A from data file */
  if (uplo == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= n; ++j)
            Vscanf("%lf", &A_UPPER(i,j));
        }
      Vscanf("%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= i; ++j)
            Vscanf("%lf", &A_LOWER(i,j));
        }
      Vscanf("%*[^\n] ");
    }
  /* Read type of job to be performed */
  Vscanf(" ' %1s '%*[^\n] ", job_char);
  if (*(unsigned char *)job_char == 'V')
    job = Nag_EigVecs;
  else
    job = Nag_DoNothing;
  /* Calculate all the eigenvalues and eigenvectors of A */
  /* nag_dspevd (f08gcc).
   * All eigenvalues and optionally all eigenvectors of real
   * symmetric matrix, packed storage (divide-and-conquer)
   */
  nag_dspevd(order, job, uplo, n, ap, w, z, pdz, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_dspevd (f08gcc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print eigenvalues and eigenvectors */
  Vprintf("Eigenvalues \n");
  for (i = 0; i < n; ++i)
    Vprintf(" %8.4lf",w[i]);
  Vprintf("\n");
  /* nag_gen_real_mat_print (x04cac).
   * Print real general matrix (easy-to-use)
   */
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
                         z, pdz, "Eigenvectors", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
 END:
  if (ap) NAG_FREE(ap);
  if (w) NAG_FREE(w);
  if (z) NAG_FREE(z);
  return exit_status;
}