Function perp

code/geometry/primitives.cpp:25–25

  return asin(cross(b - a, c - b) / abs(b - a) / abs(c - b)); }
double angle(P(p)) { return atan2(imag(p), real(p)); }
point perp(P(p)) { return point(-imag(p), real(p)); }
double progress(P(p), L(a, b)) {
  if (abs(real(a) - real(b)) < EPS)
    return (imag(p) - imag(a)) / (imag(b) - imag(a));