1 /* vector2.h */ 2 #ifndef _VECTOR2_H_ 3 #define _VECTOR2_H_ 4 typedef struct vector2{ 5 double x; 6 double y; 7 } vector2; 8 9 vector2 makevector2(double x, double y); 10 vector2 vec2plus(vector2 a, vector2 b); 11 void vec2add(vector2* a, vector2* b); 12 vector2 vec2minus(vector2 a, vector2 b); 13 void vec2subtract(vector2* a, vector2* b); 14 double vec2dot(vector2 a, vector2 b); 15 16 #endif 17