/* nag_make_indices (m01zac) Example Program.

 *

 * Copyright 1990 Numerical Algorithms Group.

 *

 * Mark 2 revised, 1992.

 * Mark 5 revised, 1998.

 * Mark 7 revised, 2001.

 * Mark 8 revised, 2004.

 *

 */



#include <nag.h>

#include <stdio.h>

#include <nag_stdlib.h>

#include <nag_stddef.h>

#include <nagm01.h>





#ifdef __cplusplus

extern "C"

{

#endif

  static Integer NAG_CALL compare(const Nag_Pointer a,const Nag_Pointer b)

  {

    double x = *((const double *)a);

    double y = *((const double *)b);

    return (x<y ? -1 : (x==y ? 0 : 1));

  }

#ifdef __cplusplus

}

#endif



#define VEC(I,J) vec[(I)*tdvec + J]

int main(void)

{

  Integer exit_status=0, tdvec;

  NagError fail;

  double *vec=0;

  size_t i, j, m, n, *rank=0;



  INIT_FAIL(fail);

  /* Skip heading in data file */

  Vscanf("%*[^\n]");

  Vprintf("nag_make_indices (m01zac) Example Program Results\n");

  Vscanf("%u%u", &m, &n);

  if (m>=1 &&  n>=1 && n<=n)

    {

      if ( !( vec = NAG_ALLOC(m*n, double))  ||

           !( rank = NAG_ALLOC(m, size_t)) )

        {

          Vprintf("Allocation failure\n");

          exit_status = -1;

          goto END;

        }

      tdvec = n;

    }

  else

    {

      Vprintf("Invalid m or n.\n");

      exit_status = 1;

      return exit_status;

    }

  for (i=0; i<m; ++i)

    for (j=0; j<n; ++j)

      Vscanf("%lf", &VEC(i,j));

  /* nag_rank_sort (m01dsc).

   * Rank sort of set of values of arbitrary data type

   */

  nag_rank_sort((Pointer) vec, m, (ptrdiff_t)(n*sizeof(double)), compare,

                Nag_Ascending, rank, &fail);

  if (fail.code != NE_NOERROR)

    {

      Vprintf("Error from nag_rank_sort (m01dsc).\n%s\n", fail.message);

      exit_status = 1;

      goto END;

    }

  /* nag_make_indices (m01zac).

   * Inverts a permutation converting a rank vector to an

   * index vector or vice versa

   */

  nag_make_indices(rank, m, &fail);

  if (fail.code != NE_NOERROR)

    {

      Vprintf("Error from nag_make_indices (m01zac).\n%s\n", fail.message);

      exit_status = 1;

      goto END;

    }

  Vprintf("Matrix with rows sorted according to column 1\n");

  for (i=0; i<m; ++i)

    {

      for (j=0; j<n; ++j)

        Vprintf(" %7.1f ", VEC(rank[i],j));

      Vprintf("\n");

    }

 END:

  if (vec) NAG_FREE(vec);

  if (rank) NAG_FREE(rank);

  return exit_status;

}