public Vector4f subtract(Vector4f vec) {
        return new Vector4f(x - vec.x, y - vec.y, z - vec.z, w - vec.w);
    }
<code>subtract</code> subtracts the values of a given vector from those
of this vector creating a new vector object. If the provided vector is
null, null is returned.

@param vec
           the vector to subtract from this vector.
@return the result vector.
jme3-core/src/main/java/com/jme3/math/Vector4f.java