This turns out not to be a full differential operator in the usual sense but has many of the desired properties.

We next give the example of differential operators with constant coefficients.

The exponential over a differential operator is understood as a power series.

The reason for this is that for many purposes there are not enough differential operators.

Similar differential operators can be applied to the fields, to find:

He has made notable contributions to the study of partial differential operators.

Now, we must continue the differential operator to the central point x in the punctured neighborhood.

This extension of the above differential operator need not be constrained only to real powers.

The most common differential operator is the action of taking the derivative itself.

In connection with differential operators it is common to use inner products and integration by parts.