高手帮忙弄个分段函数图像
 

刚学matlab，请高手帮忙弄个分段函数图像

%例如令a=2
a=2;
x=[0.5 1 1 5 5 8 8 9 9 11 11 13 13 14 14 15 15 16 16 20];
x_0=0:25;
y_0=zeros(1,26);
y=[-a -a a a -a -a a a -a -a a a -a -a a a -a -a a a ];
plot(x,y,x_0,y_0)
text(1.1,-0.18,'1');
text(5.1,-0.18,'5');
text(10.1,-0.18,'10');
text(15.1,-0.18,'15');
axis([0,25,-2*a,2*a])

clc
clear
x=0:0.01:10;

a=2;
y=-a*(x<=0)+(x>=1 & x<=5)*a-a*(x>=5 & x<=8);

plot(x,y)
axis([0 10,-3 3])

楼上 你的 “*” 要变成 “.*” 才可以吧:cool:

弄个完整的!
 

clc
clear
xk=[0,1,5,8,9,11,13,14,15,16,20];
x=0:0.01:xk(end); y=zeros(size(x));
a=2;
for i=1:(length(xk)-1)
y=y+(-1)^i*a*(x>=xk(i) &x<xk(i+1));
end
plot(x,y)
axis([0,20 ,-3 3])

楼上各位，坐标轴在哪呢？