code: @Pure
  	public static Point2d L1_L4(double x, double y) {
  		final Point2d ntfLambdaPhi = NTFLambert_NTFLambdaPhi(x, y,
  				LAMBERT_1_N,
  				LAMBERT_1_C,
  				LAMBERT_1_XS,
  				LAMBERT_1_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 I coordinate to
  France Lambert IV coordinate.
  
  @param x is the coordinate in France Lambert I
  @param y is the coordinate in France Lambert I
  @return the France Lambert IV coordinate.