A. K. Head, C.S. I. R. 0. Division of Tribophysics,

Melbourne, Australia

The evaluation of functions by recursion is a technique which

is not often used in computing, but it has proved to be the

solution to two different problems in FOCAL. The first was

the need for circular functions which were more accurate

than the internal functions when using 4-word arithmetic

(when the internal functions have only 3-word accuracy).

The second was the need for functions which occupy less

memory than the corresponding internal functions. A selec-

tion of some of the circular and hyperbolic functions which

have been used are included in this progrQm.