function f = jagged(x,n,a,s)
%JAGGED Computes an approximation of a continuous nowhere differentiable
% function.
%
% jagged(x,n,a,s) is given by
% __
% \ | n (s-2)m m
% > a sin(a x)
% /__| m=0
%
% In the limit as n->infinity this gives a continuous nowhere differentiable
% function if a>1 and 1