code: public void jacobianIntrinsics(double camX, double camY, double camZ,
  								   @Nonnull double calibX[], @Nonnull double calibY[]) {
  		funcIntrinsic.X.set(camX,camY,camZ);
  
  		jacobian.reshape(2,numIntrinsic);
  		numericalIntrinsic.process(intrinsic,jacobian);
  
  		for (int i = 0; i < numIntrinsic; i++) {
  			calibX[i] = jacobian.data[i];
  			calibY[i] = jacobian.data[i+numIntrinsic];
  		}
  
  		// make sure its intrinsic parameters have not been modified
  		model.setIntrinsic(intrinsic,0);
  	}
docs: Computes Jacobian for intrinsic parameters
  
  @param camX 3D point in camera reference frame
  @param camY 3D point in camera reference frame
  @param camZ 3D point in camera reference frame
  @param calibX (Output) Partial of projected x' relative to calibration parameters. length N
  @param calibY (Output) Partial of projected y' relative to calibration parameters. length N