vect sub(const vect &a, const vect &b) { return vect(a.readx() - b.readx(), a.ready() - b.ready(), a.readz() - b.readz()); }
vect vmlpt(const vect &a, const vect &b) { return vect(((a.ready()*b.readz()) - (a.readz()*b.ready())), ((a.readz()*b.readx()) - (a.readx()*b.readz())), ((a.readx()*b.ready()) - (a.ready()*b.readx()))); }
double smlpt(const vect& a, const vect& b) { return a.readx()*b.readx() + a.ready()*b.ready() + a.readz()*b.readz(); }