code: public static SteerableCoefficients polynomial( int order ) {
  		if( order == 1 )
  			return new PolyOrder1();
  		else if( order == 2 )
  			return new PolyOrder2();
  		else if( order == 3 )
  			return new PolyOrder3();
  		else if( order == 4 )
  			return new PolyOrder4();
  		else
  			throw new IllegalArgumentException("Only supports orders 1 to 4");
  	}
docs: Coefficients for even or odd parity polynomials.
  
  @param order order of the polynomial.
  @return Steering coeficient.