function crudeplot(u)
n=length(u);
x=.001:.001:.999;
plot(x,fn(x))
hold on
for v=u
    plot([ v-1/(2*n) v-1/(2*n) v+1/(2*n) v+1/(2*n)],[0 fn(v) fn(v) 0])
end
  hold off
  