你可以试试换个思路，先把f(x)下区域全部涂蓝，再把y = 1下区域全部涂绿，最后把f(x)与y = 1下的交集涂白
( A# F- c% f; a& W3 Qx = 0:1:20;
y = 2*rand(1,21);
6 ]; Q5 R1 P: v' }/ R5 n  E- Z  ]7 lxi = 0:1e-2:20;
yi = interp1(x,y,xi,'linear');
close all;hold on
/ [' A8 i: E% s6 ^area(xi(yi>1),yi(yi>1),'FaceColor','b')
" m( H# ]; N" Sarea(xi(yi<1),0.*xi(yi<1)+1,'FaceColor','g')
area(xi,bsxfun(@min, yi, 1),'FaceColor','w')
plot(xi,yi,'k-','LineWidth',2)