Matlab - Plotting rectangle without using rectangle function

Question

How do i plot a rectangle using the plot function. I cant use rectangle(). I currently am using

theta2 = linspace(0,2*pi,5);
plot(radius.*cos(theta2)+xCentre,radius.*sin(theta2)+yCentre,'k');

but this plots a diamond rather than a rectangle.

Answer 1

Here is the code for drawing rectangle without using rectangle()

length=5;
width=2;
xCentre=0;
yCentre=0;

u=[-1 1 1 -1];
x=[u u(1)].*(length/2);
u=circshift(u,[0 -1]);
y=[u u(1)].*(width/2);
plot(x,y,'k');
xlim([x(1)-2,x(2)+2]);
ylim([y(3)-2,y(2)+2])