# include <cstdlib>
# include <iostream>
# include <iomanip>
# include <cmath>
# include <ctime>

using namespace std;

int main ( );
double cpu_time ( );
int *find_closest1 ( int m, int nr, double r[], int ns, double s[] );
double *r8mat_uniform_01_new ( int m, int n, int &seed );
void timestamp ( );

//****************************************************************************80

int main ( )

//****************************************************************************80
//
//  Purpose:
//
//    TEST_NEAREST compares the performance of nearest neighbor routines.
//
//  Discussion:
//
//    We are given R, a set of NR points in M dimensions.
//
//    We are given S, a set of NS points in M dimensions.
//
//    For each S(I) in S, we seek the index J of the point R(J)
//    which is nearest to S(I) over all points in R.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license.
//
//  Modified:
//
//    26 December 2012
//
//  Author:
//
//    John Burkardt
//
//  Local parameters:
//
//    Local, int M, the spatial dimension.
//
//    Local, int NR, the number of data points.
//
//    Local, int NS, the number of sample points.
//
//    Local, double R[M*NR], the data points.
//
//    Local, double S[M*NS], the sample points. 
//
{
  int m;
  int m_test;
  int m_test_data[3] = { 2, 4, 8 };
  int m_test_num = 3;
  int *nearest;
  int nr;
  int nr_test_data[6] = {
    1000000, 100000, 10000,  1000,    100,      10 };
  int n_test_num = 6;
  int ns;
  int ns_test_data[6] = {
      10,    100,  1000, 10000, 100000, 1000000 };
  double *r;
  double *s;
  int seed;
  double t1;
  double t2;
  int test;

  timestamp ( );
  cout << "\n";
  cout << "TEST_NEAREST:\n";
  cout << "  C++ version\n";
  cout << "  Consider various nearest neighbor algorithms.\n";

  for ( m_test = 0; m_test < m_test_num; m_test++ )
  {
    m = m_test_data[m_test];

    for ( test = 0; test < n_test_num; test++ )
    {
      nr = nr_test_data[test];
      ns = ns_test_data[test];

      seed = 123456789;
      s = r8mat_uniform_01_new ( m, ns, seed );
      r = r8mat_uniform_01_new ( m, nr, seed );

      cout << "\n";
      cout << "  M = " << m << ", NR = " << nr << ",  NS = " << ns << "\n";

      t1 = cpu_time ( );
      nearest = find_closest1 ( m, nr, r, ns, s );
      t2 = cpu_time ( );
      cout << "  #1 time: " << t2 - t1
           << ",  size = " << ns
           << ",  i[0] = " << nearest[0] << "\n";

      delete [] nearest;
      delete [] r;
      delete [] s;
    }
  }
//
//  Terminate.
//
  cout << "\n";
  cout << "TEST_NEAREST\n";
  cout << "  Normal end of execution.\n";
  cout << "\n";
  timestamp ( );

  return 0;
}
//****************************************************************************80

double cpu_time ( )

//****************************************************************************80
//
//  Purpose:
// 
//    CPU_TIME reports the elapsed CPU time.
//
//  Discussion:
//
//    The data available to this routine through "CLOCK" is not very reliable,
//    and hence the values of CPU_TIME returned should not be taken too 
//    seriously, especially when short intervals are being timed.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license. 
//
//  Modified:
//
//    23 September 2008
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    Output, double CPU_TIME, the current total elapsed CPU time in second.
//
{
  double value;

  value = ( double ) clock ( ) 
        / ( double ) CLOCKS_PER_SEC;

  return value;
}
//****************************************************************************80

int *find_closest1 ( int m, int nr, double r[], int ns, double s[] )

//****************************************************************************80
//
//  Purpose:
//
//    FIND_CLOSEST1 finds the nearest R point to each S point.
//
//  Discussion:
//
//    We are given R, a set of NR points in M dimensions.
//
//    We are given S, a set of NS points in M dimensions.
//
//    For each S(I) in S, we seek the index J of the point R(J)
//    which is nearest to S(I) over all points in R.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license.
//
//  Modified:
//
//    26 December 2012
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    Input, int M, the spatial dimension.
//
//    Input, int NR, the number of data points.
//
//    Input, double R[M*NR], the data points.
//
//    Input, int NS, the number of sample points.
//
//    Input, double S[M*NS], the sample points.
//
//    Output, int FIND_CLOSEST1[NS], the index of the nearest data point.
//
{
  double dist_sq;
  double dist_sq_min;
  int i;
  int jr;
  int js;
  int *nearest;
  static double r8_huge = 1.0E+30;

  nearest = new int[ns];

  for ( js = 0; js < ns; js++ )
  {
    dist_sq_min = r8_huge;
    nearest[js] = -1;
    for ( jr = 0; jr < nr; jr++ )
    {
      dist_sq = 0.0;
      for ( i = 0; i < m; i++ )
      {
        dist_sq = dist_sq + pow ( r[i+jr*m] - s[i+js*m], 2 );
      }
      if ( dist_sq < dist_sq_min )
      {
        dist_sq_min = dist_sq;
        nearest[js] = jr;
      }
    }
  }

  return nearest;
}
//****************************************************************************80

double *r8mat_uniform_01_new ( int m, int n, int &seed )

//****************************************************************************80
//
//  Purpose:
//
//    R8MAT_UNIFORM_01_NEW returns a unit pseudorandom R8MAT.
//
//  Discussion:
//
//    An R8MAT is a doubly dimensioned array of R8's,  stored as a vector
//    in column-major order.
//
//    This routine implements the recursion
//
//      seed = 16807 * seed mod ( 2^31 - 1 )
//      unif = seed / ( 2^31 - 1 )
//
//    The integer arithmetic never requires more than 32 bits,
//    including a sign bit.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license.
//
//  Modified:
//
//    03 October 2005
//
//  Author:
//
//    John Burkardt
//
//  Reference:
//
//    Paul Bratley, Bennett Fox, Linus Schrage,
//    A Guide to Simulation,
//    Springer Verlag, pages 201-202, 1983.
//
//    Bennett Fox,
//    Algorithm 647:
//    Implementation and Relative Efficiency of Quasirandom
//    Sequence Generators,
//    ACM Transactions on Mathematical Software,
//    Volume 12, Number 4, pages 362-376, 1986.
//
//    Philip Lewis, Allen Goodman, James Miller,
//    A Pseudo-Random Number Generator for the System/360,
//    IBM Systems Journal,
//    Volume 8, pages 136-143, 1969.
//
//  Parameters:
//
//    Input, int M, N, the number of rows and columns.
//
//    Input/output, int &SEED, the "seed" value.  Normally, this
//    value should not be 0, otherwise the output value of SEED
//    will still be 0, and R8_UNIFORM will be 0.  On output, SEED has
//    been updated.
//
//    Output, double R8MAT_UNIFORM_01_NEW[M*N], a matrix of pseudorandom values.
//
{
  int i;
  int j;
  int k;
  double *r;

  r = new double[m*n];

  for ( j = 0; j < n; j++ )
  {
    for ( i = 0; i < m; i++ )
    {
      k = seed / 127773;

      seed = 16807 * ( seed - k * 127773 ) - k * 2836;

      if ( seed < 0 )
      {
        seed = seed + 2147483647;
      }
      r[i+j*m] = ( double ) ( seed ) * 4.656612875E-10;
    }
  }

  return r;
}
//****************************************************************************80

void timestamp ( )

//****************************************************************************80
//
//  Purpose:
//
//    TIMESTAMP prints the current YMDHMS date as a time stamp.
//
//  Example:
//
//    31 May 2001 09:45:54 AM
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license. 
//
//  Modified:
//
//    24 September 2003
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    None
//
{
# define TIME_SIZE 40

  static char time_buffer[TIME_SIZE];
  const struct tm *tm;
  time_t now;

  now = time ( NULL );
  tm = localtime ( &now );

  strftime ( time_buffer, TIME_SIZE, "%d %B %Y %I:%M:%S %p", tm );

  cout << time_buffer << "\n";

  return;
# undef TIME_SIZE
}