tangent method
Vector3
tangent(
- Vector3 a
Get the tangent of this vector with respect to a
Implementation
Vector3 tangent (Vector3 a ) {
double ax = a.x, ay = a.y, az = a.z;
x = ay * ax - az * az;
y = - az * ay - ax * ax;
z = ax * az + ay * ay;
return this;
}