/* nag_dopgtr (f08gfc) 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  ap_len, i, j, n, pdz, d_len, e_len, tau_len;
  Integer  exit_status=0;
  NagError fail;
  Nag_UploType  uplo;
  Nag_OrderType order;
  /* Arrays */
  char   uplo_char[2];
  double *ap=0, *d=0, *e=0, *tau=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("f08gfc Example Program Results\n\n");

  /* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%ld%*[^\n] ", &n);
#ifdef NAG_COLUMN_MAJOR
  pdz = n;
#else
  pdz = n;
#endif
  ap_len = n*(n+1)/2;
  tau_len = n-1;
  d_len = n;
  e_len = n-1;
  /* Allocate memory */
  if ( !(ap = NAG_ALLOC(ap_len, double)) ||
       !(d = NAG_ALLOC(d_len, double)) ||
       !(e = NAG_ALLOC(e_len, double)) ||
       !(tau = NAG_ALLOC(tau_len, double)) ||
       !(z = NAG_ALLOC(n * n, double)) )
    {
      Vprintf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A from data file */
  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;
    }
  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] ");
    }

  /* Reduce A to tridiagonal form T = (Q**T)*A*Q */
  f08gec(order, uplo, n, ap, d, e, tau, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08gec.\n%s\n", fail.message);
      exit_status = 1;
    }

  /* Form Q explicitly, storing the result in Z */
  f08gfc(order, uplo, n, ap, tau, z, pdz, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08gfc.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Calculate all the eigenvalues and eigenvectors of A */
  f08jec(order, Nag_UpdateZ, n, d, e, z, pdz, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08jec.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print eigenvalues and eigenvectors */
  Vprintf("Eigenvalues\n");
  for (i = 1; i <= n; ++i)
    Vprintf("%8.4f%s", d[i-1], i%8==0 ?"\n":" ");
  Vprintf("\n\n");
  x04cac(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, z, pdz,
         "Eigenvectors", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from x04cac.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
 END:
  if (ap) NAG_FREE(ap);
  if (d) NAG_FREE(d);
  if (e) NAG_FREE(e);
  if (tau) NAG_FREE(tau);
  if (z) NAG_FREE(z);

  return exit_status;
}