/* nag_dormhr (f08ngc) 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, m, n, pda, pdh, pdvl, pdvr, pdz;
  Integer  tau_len, ifaill_len, ifailr_len, select_len, w_len;
  Integer  exit_status=0;
  double   thresh;
  NagError fail;
  Nag_OrderType order;
  /* Arrays */
  double  *a=0, *h=0, *vl=0, *vr=0, *z=0, *wi=0, *wr=0, *tau=0;
  Integer *ifaill=0, *ifailr=0;
  Boolean *select=0;

#ifdef NAG_COLUMN_MAJOR
#define A(I,J) a[(J-1)*pda + I - 1]
#define H(I,J) h[(J-1)*pdh + I - 1]
  order = Nag_ColMajor;
#else
#define A(I,J) a[(I-1)*pda + J - 1]
#define H(I,J) h[(I-1)*pdh + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);
  Vprintf("f08ngc Example Program Results\n\n");

  /* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%ld%*[^\n] ", &n);
#ifdef NAG_COLUMN_MAJOR
  pda = n;
  pdh = n;
  pdvl = n;
  pdvr = n;
  pdz = 1;
#else
  pda = n;
  pdh = n;
  pdvl = n;
  pdvr = n;
  pdz = 1;
#endif
  tau_len = n;
  w_len = n;
  ifaill_len = n;
  ifailr_len = n;
  select_len = n;

  /* Allocate memory */
  if ( !(a = NAG_ALLOC(n * n, double)) ||
       !(h = NAG_ALLOC(n * n, double)) ||
       !(vl = NAG_ALLOC(n * n, double)) ||
       !(vr = NAG_ALLOC(n * n, double)) ||
       !(z = NAG_ALLOC(1 * 1, double)) ||
       !(wi = NAG_ALLOC(w_len, double)) ||
       !(wr = NAG_ALLOC(w_len, double)) ||
       !(ifaill = NAG_ALLOC(ifaill_len, Integer)) ||
       !(ifailr = NAG_ALLOC(ifaill_len, Integer)) ||
       !(select = NAG_ALLOC(select_len, Boolean)) ||
       !(tau = NAG_ALLOC(tau_len, double)) )
    {
      Vprintf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
  /* Read A from data file */
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= n; ++j)
        Vscanf("%lf", &A(i,j));
    }
  Vscanf("%*[^\n] ");
  Vscanf("%lf%*[^\n] ", &thresh);

  /* Reduce A to upper Hessenberg form */
  f08nec(order, n, 1, n, a, pda, tau, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08nec.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Copy A to H */
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= n; ++j)
        H(i,j) = A(i,j);
    }

  /* Calculate the eigenvalues of H (same as A) */
  f08pec(order, Nag_EigVals, Nag_NotZ, n, 1, n, h, pdh, wr,
         wi, z, pdz, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08pec.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print eigenvalues */
  Vprintf(" Eigenvalues\n");
  for (i = 0; i < n; ++i)
    Vprintf(" (%8.4f,%8.4f)\n", wr[i], wi[i]);
  Vprintf("\n");
  for (i = 0; i < n; ++i)
    select[i] = (wr[i] < thresh);
  /* Calculate the eigenvectors of H (as specified by SELECT), */
  /* storing the result in VR */
  f08pkc(order, Nag_RightSide, Nag_HSEQRSource, Nag_NoVec, select,
         n, a, pda, wr, wi, vl, pdvl, vr, pdvr, n, &m, ifaill,
         ifailr, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08pkc.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Calculate the eigenvectors of A = Q * VR */
  f08ngc(order, Nag_LeftSide, Nag_NoTrans, n, m, 1, n, a, pda,
         tau, vr, pdvr, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f08ngc.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print Eigenvectors */
  x04cac(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, m, vr, pdvr,
         "Contents of array VR", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from x04cac.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
 END:
  if (a) NAG_FREE(a);
  if (h) NAG_FREE(h);
  if (vl) NAG_FREE(vl);
  if (vr) NAG_FREE(vr);
  if (z) NAG_FREE(z);
  if (wi) NAG_FREE(wi);
  if (wr) NAG_FREE(wr);
  if (ifaill) NAG_FREE(ifaill);
  if (ifailr) NAG_FREE(ifailr);
  if (select) NAG_FREE(select);
  if (tau) NAG_FREE(tau);
  return exit_status;
}