# include <float.h>
# include <math.h>
# include <stdio.h>
# include <stdlib.h>

# include "closest_point_brute.h"

/******************************************************************************/

void closest_point_brute ( int m, int nr, double r[], double s[], 
  int *near_index, double *near_dist )

/******************************************************************************/
/*
  Purpose:

    closest_point_brute() finds the nearest R point to an S point.

  Discussion:

    We are given R, a set of NR points in M dimensions.

    We are given S, a point in M dimensions.

    We seek the index J of the point R(J)
    which is nearest to S over all points in R.

  Licensing:

    This code is distributed under the MIT license.

  Modified:

    14 August 2024

  Author:

    John Burkardt

  Input:

    int M, the spatial dimension.

    int NR, the number of data points.

    double R[M*NR], the data points.

    double S[M], the point whose nearest R value is desired.

  Output:

    int *near_index: the index of the nearest data point.

    double *near_dist: the distance of the nearest data point.
*/
{
  double dist_sq;
  int i;
  int jr;

  *near_dist = DBL_MAX;
  *near_index = -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], 2 );
    }

    if ( dist_sq < *near_dist )
    {
      *near_dist = dist_sq;
      *near_index = jr;
    }
  }

  *near_dist = sqrt ( *near_dist );

  return;
}