/* nag_dspgst (f08tec) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagf08.h>

int main(void)
{
  /* Scalars */
  Integer  i, j, n, ap_len, bp_len, 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, *bp=0, *d=0, *e=0, *tau=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]
#define B_UPPER(I,J) bp[J*(J-1)/2 + I - 1]
#define B_LOWER(I,J) bp[(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]
#define B_LOWER(I,J) bp[I*(I-1)/2 + J - 1]
#define B_UPPER(I,J) bp[(2*n-I)*(I-1)/2 + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);
  Vprintf("f08tec Example Program Results\n\n");

  /* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%ld%*[^\n] ", &n);
  ap_len = n * (n +1 )/2;
  bp_len = n * (n +1 )/2;
  d_len = n;
  e_len = n-1;
  tau_len = n;

  /* Allocate memory */
  if ( !(ap = NAG_ALLOC(ap_len, double)) ||
       !(bp = NAG_ALLOC(bp_len, double)) ||
       !(d = NAG_ALLOC(d_len, double)) ||
       !(e = NAG_ALLOC(e_len, double)) ||
       !(tau = NAG_ALLOC(tau_len, double)) )
    {
      Vprintf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A and B 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] ");
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= n; ++j)
            Vscanf("%lf", &B_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] ");
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= i; ++j)
            Vscanf("%lf", &B_LOWER(i,j));
        }
      Vscanf("%*[^\n] ");
    }
  /* Compute the Cholesky factorization of B */
  f07gdc(order, uplo, n, bp, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f07gdc.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Reduce the problem to standard form C*y = lambda*y, storing */
  /* the result in A */
  f08tec(order, Nag_Compute_1, uplo, n, ap, bp, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08tec.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Reduce C to tridiagonal form T = (Q**T)*C*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;
      goto END;
    }
  /* Calculate the eigenvalues of T (same as C) */
  f08jfc(n, d, e, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08jfc.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print eigenvalues */
  Vprintf("Eigenvalues\n");
  for (i = 1; i <= n; ++i)
    Vprintf("%8.4f%s", d[i-1], i%9==0 || i==n ?"\n":" ");
  Vprintf("\n");
 END:
  if (ap) NAG_FREE(ap);
  if (bp) NAG_FREE(bp);
  if (d) NAG_FREE(d);
  if (e) NAG_FREE(e);
  if (tau) NAG_FREE(tau);

  return exit_status;
}