How to create a graph with a shaded area ?

how to create a graph with a shaded area (rectangle with diagonal lines) ? I would like to create a graph (in MATLAB) similar to this:

Answer 1

[Azzi Abdelmalek]

a=8; % Rectangle width
b=15; % Rectangle height
n=8; % Number of stripes is equal to 2*n
plot([0 a a 0 0],[0 0 b b 0],'k','linewidth',4)
set(gca,'xlim',[0 a*1.2],'ylim',[0 b*1.2]);
x11=[zeros(1,n) linspace(0,a,n);linspace(0,a,n) ones(1,n)*a]
y11=[linspace(0,b,n) b*ones(1,n);zeros(1,n) b-fliplr(linspace(0,b,n))]
hold on
plot(x11 ,y11,'k','linewidth',4)

[Jesus]

Azzi Abdelmalek, thanks for the reply.

[Jesus]

Now I'm trying to make a graph like this:

What I have to add the above code to generate this graph ? I tried several modicações in the above code, but could not make the graph.