r.x=rand_get_double(&(moldyn->random))*x;
r.y=rand_get_double(&(moldyn->random))*y;
r.z=rand_get_double(&(moldyn->random))*z;
r.x=rand_get_double(&(moldyn->random))*x;
r.y=rand_get_double(&(moldyn->random))*y;
r.z=rand_get_double(&(moldyn->random))*z;