code: @Pure
  	public static Point2d L2_L4(double x, double y) {
  		final Point2d ntfLambdaPhi = NTFLambert_NTFLambdaPhi(x, y,
  				LAMBERT_2_N,
  				LAMBERT_2_C,
  				LAMBERT_2_XS,
  				LAMBERT_2_YS);
  		return NTFLambdaPhi_NTFLambert(
  				ntfLambdaPhi.getX(), ntfLambdaPhi.getY(),
  				LAMBERT_4_N,
  				LAMBERT_4_C,
  				LAMBERT_4_XS,
  				LAMBERT_4_YS);
  	}
docs: This function convert France Lambert II coordinate to
  France Lambert IV coordinate.
  
  @param x is the coordinate in France Lambert II
  @param y is the coordinate in France Lambert II
  @return the France Lambert IV coordinate.