Three commonly used types of three-dimensional molecular models are reviewed together with their suitability for two-dimensional computer representation. A new algorithm is described which allows perspective, hidden-line drawings to be made of space-filling models, and which takes advantage of the spherical symmetries of these models.

A powerful means of analyzing nonlinear systems is provided by the Wiener functional expansion. However, this technique has not been implemented widely in experimental situations because of the difficulties associated with measuring the kernels of the system, which constitutes the analysis problem. A new method of measuring the kernels is described here in which the Walsh functions are used as the set of orthogonal functions with which the kernels are expanded. The multiplicative properties of the Walsh functions and the fast Walsh-Fourier transform make the measurement scheme very efficient.