Changed the first iterator of PersistenceDiagram to accept dimension as well. Modified documentation.
#include "grid2D.h"
#include <iostream>
int main()
{
Grid2D grid(40,60);
int i = 0;
for (int x = 0; x < 40; ++x)
for (int y = 0; y < 60; ++y)
{
grid(x,y) = i++;
}
std::cout << grid(20,30) << std::endl;
std::cout << grid << std::endl;
}