Example #1
0
//AntiProjection returns a vector in the direction of ref with the magnitude of
//a vector A would have if |test| was the magnitude of its projection
//in the direction of test.
func AntiProjection(test, ref *v3.Matrix) *v3.Matrix {
	rr, _ := ref.Dims()
	testnorm := test.Norm(0)
	Uref := v3.Zeros(rr)
	Uref.Unit(ref)
	scalar := test.Dot(Uref)
	scalar = (testnorm * testnorm) / scalar
	Uref.Scale(scalar, Uref)
	return Uref
}
Example #2
0
//Angle takes 2 vectors and calculate the angle in radians between them
//It does not check for correctness or return errors!
func Angle(v1, v2 *v3.Matrix) float64 {
	normproduct := v1.Norm(0) * v2.Norm(0)
	dotprod := v1.Dot(v2)
	argument := dotprod / normproduct
	//Take care of floating point math errors
	if math.Abs(argument-1) <= appzero {
		argument = 1
	} else if math.Abs(argument+1) <= appzero {
		argument = -1
	}
	//fmt.Println(dotprod/normproduct,argument) //dotprod/normproduct, dotprod, normproduct,v1.TwoNorm(),v2.TwoNorm())
	angle := math.Acos(argument)
	if math.Abs(angle) <= appzero {
		return 0.00
	}
	return angle
}