/* nag_zpteqr (f08juc) 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(int argc, char *argv[])
{
  FILE          *fpin, *fpout;
  char          *outfile = 0;
  /* Scalars */
  Integer       i, j, n, pda, pdz, d_len, e_len, tau_len;
  Integer       exit_status = 0;
  NagError      fail;
  Nag_UploType  uplo;
  Nag_OrderType order;
  /* Arrays */
  char          nag_enum_arg[40];
  Complex       *a = 0, *tau = 0, *z = 0;
  double        *d = 0, *e = 0;

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

  INIT_FAIL(fail);

  /* Check for command-line IO options */
  fpin = nag_example_file_io(argc, argv, "-data", NULL);
  fpout = nag_example_file_io(argc, argv, "-results", NULL);
  (void) nag_example_file_io(argc, argv, "-nag_write", &outfile);
  fprintf(fpout, "nag_zpteqr (f08juc) Example Program Results\n\n");

  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%ld%*[^\n] ", &n);

  pda = n;
  pdz = n;
  tau_len = n-1;
  d_len = n;
  e_len = n-1;
  /* Allocate memory */
  if (!(a = NAG_ALLOC(n * n, Complex)) ||
      !(tau = NAG_ALLOC(tau_len, Complex)) ||
      !(z = NAG_ALLOC(n * n, Complex)) ||
      !(d = NAG_ALLOC(d_len, double)) ||
      !(e = NAG_ALLOC(e_len, double)))
    {
      fprintf(fpout, "Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A from data file */
  fscanf(fpin, "%s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg);
  if (uplo == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= n; ++j)
            fscanf(fpin, " ( %lf , %lf )", &A(i, j).re, &A(i, j).im);
        }
      fscanf(fpin, "%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= i; ++j)
            fscanf(fpin, " ( %lf , %lf )", &A(i, j).re, &A(i, j).im);
        }
      fscanf(fpin, "%*[^\n] ");
    }

  /* Reduce A to tridiagonal form T = (Q**H)*A*Q */
  /* nag_zhetrd (f08fsc).
   * Unitary reduction of complex Hermitian matrix to real
   * symmetric tridiagonal form
   */
  nag_zhetrd(order, uplo, n, a, pda, d, e, tau, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_zhetrd (f08fsc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Copy A into Z */
  if (uplo == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= n; ++j)
            {
              Z(i, j).re = A(i, j).re;
              Z(i, j).im = A(i, j).im;
            }
        }
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= i; ++j)
            {
              Z(i, j).re = A(i, j).re;
              Z(i, j).im = A(i, j).im;
            }
        }
    }

  /* Form Q explicitly, storing the result in Z */
  /* nag_zungtr (f08ftc).
   * Generate unitary transformation matrix from reduction to
   * tridiagonal form determined by nag_zhetrd (f08fsc)
   */
  nag_zungtr(order, uplo, n, z, pdz, tau, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_zungtr (f08ftc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Calculate all the eigenvalues and eigenvectors of A */
  /* nag_zpteqr (f08juc).
   * All eigenvalues and eigenvectors of real symmetric
   * positive-definite tridiagonal matrix, reduced from
   * complex Hermitian positive-definite matrix
   */
  nag_zpteqr(order, Nag_UpdateZ, n, d, e, z, pdz, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_zpteqr (f08juc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print eigenvalues and eigenvectors */
  fprintf(fpout, " Eigenvalues\n");
  for (i = 1; i <= n; ++i)
    fprintf(fpout, "%7.4f%s", d[i-1], i%4 == 0?"\n":"            ");
  fprintf(fpout, "\n");
  /* nag_gen_complx_mat_print_comp (x04dbc).
   * Print complex general matrix (comprehensive)
   */
  if (outfile) fclose(fpout);
  nag_gen_complx_mat_print_comp(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n,
                                n, z, pdz, Nag_BracketForm, "%7.4f",
                                "Eigenvectors", Nag_IntegerLabels, 0,
                                Nag_IntegerLabels, 0, 80, 0, outfile, &fail);
  if (outfile && !(fpout = fopen(outfile, "a")))
    {
      exit_status = 2;
      goto END;
    }
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout,
              "Error from nag_gen_complx_mat_print_comp (x04dbc).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (a) NAG_FREE(a);
  if (tau) NAG_FREE(tau);
  if (z) NAG_FREE(z);
  if (d) NAG_FREE(d);
  if (e) NAG_FREE(e);

  return exit_status;
}