question: public Quaternion nor ( ) { float len = len2 ( ) ; if ( len != 0.f && ( Math . abs ( len - 1.0f ) > NORMALIZATION_TOLERANCE ) ) { len = ( float ) Math . sqrt ( len ) ; w /= len ; x /= len ; y /= len ; z /= len ; } return this ; }
target:  Normalizes this quaternion to unit length