#include struct ising { int Lx; // number of spins in x direction int Ly; // number of spins in y direction int N; // total number of spins int steps; // steps so far int **s; // the spins double J; // ferromagnetic coupling double T; // temperature double H; // magnetic field gsl_rng *r; // random number generator unsigned long seed; // rng seed double w[17][3]; // Boltzmann factors int **cluster; // spin cluster labels double addprobability; // probability to add like spin };