/* nag_dsteqr (f08jec) 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, n, pdz, d_len, e_len;
  Integer  exit_status=0;
  NagError fail;
  Nag_OrderType  order;
  /* Arrays */
  double *z=0, *d=0, *e=0;

#ifdef NAG_COLUMN_MAJOR
  order = Nag_ColMajor;
#else
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);
  Vprintf("f08jec Example Program Results\n\n");

  /* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%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)) )
    {
      Vprintf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
  /* Read T from data file */
  for (i = 0; i < d_len; ++i)
    Vscanf("%lf", &d[i]);
  for (i = 0; i < e_len; ++i)
    Vscanf("%lf", &e[i]);
  /* Calculate all the eigenvalues and eigenvectors of T */
  f08jec(order, Nag_InitZ, 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 = 0; i < n; ++i)
    Vprintf("  %7.4lf",d[i]);
  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 (d) NAG_FREE(d);
  if (e) NAG_FREE(e);
  if (z) NAG_FREE(z);
  return exit_status;
}