int verbosity; // print statistics every number of steps indicated by this variable
clock_t start_clock; // clock cycles done when simulation starts
struct timeval start_time; // time at which simulation starts
+ float theta; // Parameter used for Barns Hut algorithm
+ int random; //Used to randomly create bodies
} Options;
void Body_Print(Body * a, FILE * out); //Print body a
void Body_Position(Body * a); //Compute position of body a
void System_Init(System * s, const char * fileName); //Initialise System (array of bodies) from a text file
+void System_Random(System * s, int r); //Randomly create bodies
void System_Compute(System * s);
void System_Forces(System * s1, System * s2); //Compute forces for bodies in s1 due to bodies in s2 (also updates velocities)
void System_Positions(System * s); //Update positions for bodies in s1