/* nag_dsbgvx (f08ubc) 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, il = 1, iu = 1;
  Integer       i, j, ka, kb, m, n, pdab, pdbb, pdq, pdz, zsize;

  /* Arrays */
  double        *ab = 0, *bb = 0, *q = 0, *w = 0, *z = 0;
  Integer       *index = 0;
  char          nag_enum_arg[40];

  /* Nag Types */
  NagError      fail;
  Nag_OrderType order;
  Nag_UploType  uplo;
  Nag_JobType   job;

#ifdef NAG_COLUMN_MAJOR
#define AB_UPPER(I, J) ab[(J-1)*pdab + ka + I - J]
#define AB_LOWER(I, J) ab[(J-1)*pdab + I - J]
#define BB_UPPER(I, J) bb[(J-1)*pdbb + kb + I - J]
#define BB_LOWER(I, J) bb[(J-1)*pdbb + 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 + ka + J - I]
#define BB_UPPER(I, J) bb[(I-1)*pdbb + J - I]
#define BB_LOWER(I, J) bb[(I-1)*pdbb + kb + J - I]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);


  printf("nag_dsbgvx (f08ubc) Example Program Results\n\n");

  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%ld%ld%ld%*[^\n]", &n, &ka, &kb);
  if (n < 0 || ka < kb || kb < 0)
    {
      printf("Invalid n, ka or kb\n");
      exit_status = 1;
      goto END;
    }
  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);

  scanf(" %s%*[^\n]", nag_enum_arg);
  job = (Nag_JobType) nag_enum_name_to_value(nag_enum_arg);
  if (job==Nag_EigVals) {
    zsize = 1;
    pdz = 1;
  } else {
    zsize = n*n;
    pdz = n;
  }

  pdab = ka + 1;
  pdbb = kb + 1;
  pdq = n;
  /* Allocate memory */
  if (!(ab    = NAG_ALLOC((ka+1)*n, double)) ||
      !(bb    = NAG_ALLOC((kb+1)*n, double)) ||
      !(q     = NAG_ALLOC(n * n, double)) ||
      !(w     = NAG_ALLOC(n, double)) ||
      !(z     = NAG_ALLOC(zsize, double)) ||
      !(index = NAG_ALLOC(n, Integer)))
    {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read the lower and upper bounds of the interval to be searched. */
  scanf("%lf%lf%*[^\n]", &vl, &vu);

  /* Read the triangular parts of the matrices A and B from data file */
  if (uplo == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
	for (j = i; j <= MIN(i+ka, n); ++j) scanf("%lf", &AB_UPPER(i, j));
      scanf("%*[^\n]");
      for (i = 1; i <= n; ++i)
	for (j = i; j <= MIN(i+kb, n); ++j) scanf("%lf", &BB_UPPER(i, j));
    }
  else
    {
      for (i = 1; i <= n; ++i)
	for (j = MAX(1, i-ka); j <= i; ++j) scanf("%lf", &AB_LOWER(i, j));
      scanf("%*[^\n]");
      for (i = 1; i <= n; ++i)
	for (j = MAX(1, i-kb); j <= i; ++j) scanf("%lf", &BB_LOWER(i, j));
    }
  scanf("%*[^\n]");

  /* Use the default absolute error tolerance for eigenvalues. */
  abstol = 0.0;

  /* Solve the generalized symmetric eigenvalue problem A*x = lambda*B*x
   * using nag_dsbgvx (f08ubc).
   */
  nag_dsbgvx(order, job, Nag_Interval, uplo, n, ka, kb, ab, pdab, bb, pdbb, q,
	     pdq, vl, vu, il, iu, abstol, &m, w, z, pdz, index, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from in nag_dsbgvx (f08ubc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print eigensolution */
  printf("Number of eigenvalues found = %8ld\n\n", m);
  printf(" Eigenvalues\n   ");
  for (j = 0; j < m; ++j) printf(" %7.4f%s", w[j], j%6 == 5?"\n":" ");
  printf("\n");

  if (job==Nag_DoBoth) {
    /* nag_gen_real_mat_print (x04cac): Print Matrix of eigenvectors Z. */
    printf("\n");
    fflush(stdout);
    nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, m,
			   z, pdz, "Selected eigenvectors", 0, &fail);
    if (fail.code != NE_NOERROR)
      {
	printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
	       fail.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 < n; ++j)
	  printf("%8ld%s", index[j], j%6 == 5?"\n":"");
      }
  }

 END:
  if (ab)    NAG_FREE(ab);
  if (bb)    NAG_FREE(bb);
  if (q)     NAG_FREE(q);
  if (w)     NAG_FREE(w);
  if (z)     NAG_FREE(z);
  if (index) NAG_FREE(index);

  return exit_status;
}