public float angleBetween(Vector4f otherVector) {
        float dotProduct = dot(otherVector);
        float angle = FastMath.acos(dotProduct);
        return angle;
    }
<code>angleBetween</code> returns (in radians) the angle between two vectors.
It is assumed that both this vector and the given vector are unit vectors (iow, normalized).

@param otherVector a unit vector to find the angle against
@return the angle in radians.
jme3-core/src/main/java/com/jme3/math/Vector4f.java