package govector import ( "math" ) type Vector2d struct { X float64 `json:"x"` Y float64 `json:"y"` } type Point2d struct { X float64 `json:"x"` Y float64 `json:"y"` } const epsilon = 1e-7 func (p1 Point2d) sub(p2 Point2d) Vector2d { v := Vector2d{p1.X - p2.X, p1.Y - p2.Y} return v } func (v Vector2d) mag() float64 { return math.Abs(math.Sqrt(v.X*v.X + v.Y*v.Y)) }