% Script to draw figure 9.7 p. 282. Probability density as the limit of
% histograms

hold on
subplot(2,2,1)
probStairs(0.25)
subplot(2,2,2)
probStairs(0.125)
subplot(2,2,3)
probStairs(0.0625)
subplot(2,2,4)
axis([-1,1,0,0.8])
fplot('3*(1-t^2)/4',[-1,1],'k')
