Closest points

# find minimum distance between two points in set
    def find_min_dist(points)
      min = distance_point_to_point2d(points[0], points[1])
      points.each { |i|
        points.each { |j|
          j = i+1
          if (j < points.size)
            if (distance_point_to_point2d(points[i], points[j])) < min
              min = distance_point_to_point2d(points[i], points[j])
            end
          end
        }
      }
      return min
    end