close all

t=linspace(0,2*pi)
x=1*cos(t);
y=1*sin(t);
plot(x,y,'color','r')
hold on

t=linspace(0,2*pi)
x=2*cos(t);
y=1*sin(t);
plot(x,y,'color','r')

t=linspace(0,2*pi)
x=3*cos(t);
y=1*sin(t);
plot(x,y,'color','r')

t=linspace(0,2*pi)
x=4*cos(t);
y=1*sin(t);
plot(x,y,'color','r')

%
t=linspace(0,2*pi)
x=1*cos(t);
y=2*sin(t);
plot(x,y)

t=linspace(0,2*pi)
x=1*cos(t);
y=3*sin(t);
plot(x,y)

t=linspace(0,2*pi)
x=1*cos(t);
y=4*sin(t);
plot(x,y)
%
t=linspace(0,2*pi)
x=2*cos(t);
y=2*sin(t);
plot(x,y,'color','g')

t=linspace(0,2*pi)
x=2*cos(t);
y=3*sin(t);
plot(x,y,'color','g')

t=linspace(0,2*pi)
x=2*cos(t);
y=4*sin(t);
plot(x,y,'color','g')

%
t=linspace(0,2*pi)
x=3*cos(t);
y=2*sin(t);
plot(x,y,'color','m')

t=linspace(0,2*pi)
x=4*cos(t);
y=2*sin(t);
plot(x,y,'color','m')

t=linspace(0,2*pi)
x=4*cos(t);
y=4*sin(t);
plot(x,y,'color','k')

axis equal
xlabel('x-axis')
ylabel('y-axis')
zlabel('z-axis')