We combine traditional studies of inductive inference and classical continu
ous mathematics to produce a study of learning real-valued functions. We co
nsider two possible ways to model the learning by example of functions with
domain and range the real numbers. The first approach considers functions
as represented by computable analytic functions. The second considers arbit
rary computable functions of recursive real numbers. In each case we find n
atural examples of learnable classes of functions and unlearnable classes o
f functions. (C) 1999 Elsevier Science B.V. All rights reserved.