// Test of closest pair algorithms
// David Eppstein, UC Irvine, 19 Apr 1997
//
// Generate n vectors in R^d, with varying distances

#include "Vector.h"
#include "Random.h"
#include "Error.h"

static inline double DoubleAbs(double a)
{
	if (a < 0) return -a;
	else return a;
}

// Create new random set of vectors
VectorPointSet::VectorPointSet(unsigned long npoints, int dim)
	: PointSet(npoints), d(dim), points(new double[dim*npoints])
{
	if (points == 0) error("VectorPointSet: unable to create points");
	for (long i = 0; i < d*npoints; i++)
		points[i] = RandomDouble();
}

// Merge two clusters and replace by their median
void VectorPointSet::interact(point i, point j)
{
	for (int k = 0; k < d; k++)
		points[i*d+k] = points[j*d+k] = (points[i*d+k] + points[j*d+k])/2;
}

double VectorL1::VecDistance(double * u, double * v)
{
	double total = 0;
	for (int i = 0; i < d; i++)
		total += DoubleAbs(u[i] - v[i]);
	return total;
}

double VectorL2::VecDistance(double * u, double * v)
{
	double total = 0;
	for (int i = 0; i < d; i++) {
		double delta = u[i] - v[i];
		total += delta*delta;
	}
	return total;
}

double VectorLinf::VecDistance(double * u, double * v)
{
	double maxdif = DoubleAbs(u[0] - v[0]);
	for (int i = 1; i < d; i++) {
		double dif = DoubleAbs(u[i] - v[i]);
		if (dif > maxdif) maxdif = dif;
	}
	return maxdif;
}

double VectorDot::VecDistance(double * u, double * v)
{
	double total = 0;
	for (int i = 0; i < d; i++)
		total += u[i] + v[i];
	return total;
}