double InitTangentLineY (const Vect2& s, const double D, const int eps) {
// double x;
double y;
double sq_s = s.sqv();
double sq_D = sq(D);
if (Util::almost_equals(sq_s,sq_D)) {
// x = eps*s.y;
y = -eps*s.x;
} else {
Vect2 q = TangentLine::Q(s,D,eps);
// x = q.x;
y = q.y;
if (!q.isZero()) {
// x -= s.x;
y -= s.y;
}
}
return y;
}
double TCAS2D::nominal_tau(double B, double T, const Vect2& s, const Vect2& v, double rr) {
if (v.isZero())
return B;
return std::max(B,std::min(T,-s.dot(v) / v.sqv()-rr/2));
}