Even for proper assumptions about the function, the extrapolation can diverge severely from the function. The classic example is truncated power series representations of sin("x") and related trigonometric functions. For instance, taking only data from near the "x" = 0, we may estimate that the function behaves as sin("x") ~ "x". In the neighborhood of "x" = 0, this is an excellent estimate. Away from "x" = 0 however, the extrapolation moves arbitrarily away from the "x"-axis while sin("x") remains in the interval [−1,1]. I.e., the error increases without bound.