A typical implementation of such an operator involves defining an evaluation object whose constructor performs these intermediate calculations. The Image method then completes the computation of the operator image, while the Deriv and SecondDeriv methods complete the calculation of the derivatives. The operator image and derivatives should then be accessed through the ImageRef , DerivRef , and SecondDerivRef methods. The ImageRef method invokes Image to get the image and returns a reference to it. On subsequent calls, ImageRef merely references the stored value.
Range Returns a reference to the range of the underlying operator.
Image Computes the image of the operator at the point at which this object was created. Must be implemented by the creator of a concrete class. ImageRef Calls Image , if necessary, to compute the operator image, saves it, and returns it. Implemented in the base class. Must be implemented by the creator of a concrete class.