We give an O(n log n)-time method for finding a best k-link piecewise-
linear function approximating an n-point planar point set using the we
ll-known uniform metric to measure the error, epsilon greater than or
equal to 0. Of the approximation. Our method is based upon new charact
erizations of such functions, which we exploit to design an efficient
algorithm using a plane sweep in ''epsilon space'' followed by several
applications of the parametric-searching technique. The previous best
running time for this problem was O(n(2)).