  A coherent state representation of the expectation value of an arbitrary (but
still polynomial) normal ordered quantum operator is discussed. This serves as
a basis for developing a fast and easy-to-handle algorithm, based on series of
Hermite polynomials, for calculating such quantities. The case of single mode
field with number, coherent and squeezed states is treated in detail. Some
hints on how to extend the algorithm to multimode fields are also given.
