/* nag_zhpevx (f08gpc) Example Program.
 *
 * Copyright 2014 Numerical Algorithms Group.
 *
 * Mark 23, 2011.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <naga02.h>
#include <nagf08.h>
#include <nagx04.h>

int main(void)
{  
  /* Scalars */
  double        abstol, vl, vu;
  Integer       exit_status = 0, i, il = 0, iu = 0, j, m, n, pdz;
  /* Arrays */
  char          nag_enum_arg[40];
  Complex       *ap = 0, *z = 0;
  double        *w = 0;
  Integer       *index = 0;
  /* Nag Types */
  Nag_OrderType order;
  Nag_UploType  uplo;
  NagError      fail, fail_print;
  
#ifdef NAG_COLUMN_MAJOR
#define AP_UPPER(I, J) ap[J * (J - 1) / 2 + I - 1]
#define AP_LOWER(I, J) ap[(2 * n - J) * (J - 1) / 2 + I - 1]
#define Z(I, J) z[(J - 1) * pdz + I - 1]
  order = Nag_ColMajor;
#else
#define AP_LOWER(I, J) ap[I * (I - 1) / 2 + J - 1]
#define AP_UPPER(I, J) ap[(2 * n - I) * (I - 1) / 2 + J - 1]
#define Z(I, J) z[(I - 1) * pdz + J - 1]
  order = Nag_RowMajor;
#endif
  
  INIT_FAIL(fail);
  
  printf("nag_zhpevx (f08gpc) Example Program Results\n\n");
  
  /* Skip heading in data file */
  scanf("%*[^\n]");  
  scanf("%ld%*[^\n]", &n);

  /* Read uplo */
  scanf("%39s%*[^\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);
  
  /* Allocate memory */
  if (!(ap = NAG_ALLOC(n*(n+1)/2, Complex)) ||
      !(z = NAG_ALLOC(n*n, Complex)) ||
      !(w = NAG_ALLOC(n, double)) ||
      !(index = NAG_ALLOC(n, Integer)))
    {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
  pdz = n;
  
  /* Read the lower and upper bounds of the interval to be searched, and 
   * read the upper or lower triangular part of the matrix A from data file.
   */
  scanf("%lf%lf%*[^\n]", &vl, &vu);
  if (uplo == Nag_Upper) {
    for (i = 1; i <= n; ++i)
      for (j = i; j <= n; ++j)
        scanf(" ( %lf , %lf )", &AP_UPPER(i, j).re, &AP_UPPER(i, j).im);
    scanf("%*[^\n]");
  }
  else if (uplo == Nag_Lower) {
    for (i = 1; i <= n; ++i)
      for (j = 1; j <= i; ++j)
        scanf(" ( %lf , %lf )", &AP_LOWER(i, j).re, &AP_LOWER(i, j).im);
    scanf("%*[^\n]");
  }
  
  /* Set the absolute error tolerance for eigenvalues. 
   * With abstol set to zero, the default value is used instead. 
   */
  abstol = 0.0;
  
  /* nag_zhpevx (f08gpc).
   * Solve the Hermitian eigenvalue problem.
   */
  nag_zhpevx(order, Nag_DoBoth, Nag_Interval, uplo, n, ap, vl, vu, il, iu,
             abstol, &m, w, z, pdz, index, &fail);
  if (fail.code != NE_NOERROR && fail.code != NE_CONVERGENCE)
    {
      printf("Error from nag_zhpevx (f08gpc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  
  /* nag_complex_divide (a02cdc).
   * Normalize the eigenvectors.
   */
  for(j=1; j<=m; j++)
    for(i=n; i>=1; i--)
      Z(i, j) = nag_complex_divide(Z(i, j),Z(1, j));
        
  /* Print solution */
  printf("Number of eigenvalues found =%5ld\n", m);
  
  printf("\nEigenvalues\n");
  for (j = 0; j < m; ++j)
    printf("%8.4f%s", w[j], (j+1)%8 == 0?"\n":" ");
  printf("\n\n");
  
  /* nag_gen_complx_mat_print (x04dac).
   * Print selected eigenvectors.
   */
  INIT_FAIL(fail_print);
  fflush(stdout);
  nag_gen_complx_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, m, z,
                           pdz, "Selected eigenvectors", 0, &fail_print);
  if (fail_print.code != NE_NOERROR)
    {
      printf("Error from nag_gen_complx_mat_print (x04dac).\n%s\n",
             fail_print.message);
      exit_status = 1;
      goto END;
    }
  if (fail.code == NE_CONVERGENCE)
    {
      printf("eigenvectors failed to converge\n");
      printf("Indices of eigenvectors that did not converge\n");
      for (j = 0; j < m; ++j)
        printf("%8ld%s", index[j],(j+1)%8 == 0?"\n":" ");
    }
  
 END:
  NAG_FREE(ap);
  NAG_FREE(z);
  NAG_FREE(w);
  NAG_FREE(index);
  
  return exit_status;
}

#undef AP_UPPER
#undef AP_LOWER
#undef Z