/* nag_zhbevx (f08hpc) Example Program.
 *
 * Copyright 2011 Numerical Algorithms Group.
 *
 * Mark 23, 2011.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.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, kd, m, n, pdab, pdq,
                pdz;
  /* Arrays */
  char          nag_enum_arg[40];
  Complex       *ab = 0, *q = 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 AB_UPPER(I, J) ab[(J - 1) * pdab + kd + I - J]
#define AB_LOWER(I, J) ab[(J - 1) * pdab + I - J]
  order = Nag_ColMajor;
#else
#define AB_UPPER(I, J) ab[(I - 1) * pdab + J - I]
#define AB_LOWER(I, J) ab[(I - 1) * pdab + kd + J - I]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);

  printf("nag_zhbevx (f08hpc) Example Program Results\n\n");

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

  /* Read uplo */
  scanf("%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);

  /* Allocate memory */
  if (!(ab = NAG_ALLOC((kd+1)*n, Complex)) ||
      !(q = NAG_ALLOC(n*n, 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;
    }

  pdab = kd + 1;
  pdq = n;
  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 <= MIN(n, i + kd); ++j)
        scanf(" ( %lf , %lf )", &AB_UPPER(i, j).re, &AB_UPPER(i, j).im);
    scanf("%*[^\n]");
  }
  else if (uplo == Nag_Lower) {
    for (i = 1; i <= n; ++i)
      for (j = MAX(1, i - kd); j <= i; ++j)
        scanf(" ( %lf , %lf )", &AB_LOWER(i, j).re, &AB_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_zhbevx (f08hpc).
   * Solve the band symmetric eigenvalue problem.
   */
  nag_zhbevx(order, Nag_DoBoth, Nag_Interval, uplo, n, kd, ab, pdab, q, pdq,
             vl, vu, il, iu, abstol, &m, w, z, pdz, index, &fail);
  if (fail.code != NE_NOERROR && fail.code != NE_CONVERGENCE)
    {
      printf("Error from nag_zhbevx (f08hpc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* 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");
  
  /* 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:
  if (ab) NAG_FREE(ab);
  if (q) NAG_FREE(q);
  if (z) NAG_FREE(z);
  if (w) NAG_FREE(w);
  if (index) NAG_FREE(index);

  return exit_status;
}

#undef AB_UPPER
#undef AB_LOWER