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;
}

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 ; }
normalizes this quaternion to unit length
