这图怎么在程序里实现啊，怎么写程序啊

你好，代码仅供参考

clc;clear
x = 0:0.1:2.0;
h = 0.1;
lambda = 0.9;
% lambda = 1.0;
% lambda = 1.1;
tau = h*lambda;
u = (x<1/2)*1 + (x>=1/2)*0; % 初值
for i = 1:9 %9次迭代
    u1 = u; u2 = u;
    for j = 2:1:length(u)
        u1(j) = u(j) - (u(j)-u(j-1))/h*tau;
    end
    u = u1;
end
plot(x,u)%画出最后图像