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MATLAB
2D and 3D PLOTS

MATLAB PLOTTING

Creating Vectors
Create vector with equally spaced intervals

>> x=0:0
...
5000 1
...
5000 2
...
5000 3
...
5236 1
...
5708 2
...
6180 3
...
0000 14
...
5443 … 68
...
0000

Note: The logspace creates 7 equally distributed values between

101

and 10

2

Initial
Value

100

Length of the
increment

90

Final value

80
70
60
50
40

>> x=[0:5:100];
>> y=x;
>> plot(x,y)
>> stem(x,y)

30
20
10
0

0

10

20

30

40

50

60

70

80

90

100

90

100

100
90
80
70
60
50
40

NOTE: stem( ) is used to plot
discrete sequence data
...


>>y=x
...
8
0
...
4
0
...
^3;
>> plot(x,y)
>> stem(x,y)

-0
...
4
-0
...
8
-1
-100

-80

-60

-40

-80

-60

-40

-20

0

20

40

60

80

100

6

1

x 10

0
...
6
0
...
2

NOTE:
If the length of the increments
are small, then curve will be
more smoother
...
2
-0
...
6
-0
...
of increments
1
0
...
6

>> x=linspace(0,4*pi,100);
>> y=sin(x);
>> plot(y);

0
...
2
0
-0
...
4
-0
...
8
-1

0

10

20

30

40

50

60

70

80

90

100

2D PLOTS
To Plot the function e(-x/3) between 0≤x≤4π
1
0
...
8
0
...
6
0
...
4
0
...
2
0
...
8

>> a=linspace(0,4*pi,100);
>> b=cos(a);
>> plot(a,b);

0
...
4
0
...
2
-0
...
6
-0
...
7
0
...
5
0
...

>>y3=y1
...
3
0
...
1
0
-0
...
2
-0
...
7
0
...
5
0
...
3
0
...
1
0
-0
...
2
-0
...
8
0
...
4

f(x)-values

x=linspace(0,2*pi,100);
y=sin(x);
plot(x,y);
title('this is sinus function');
xlabel('x-values');
ylabel('f(x)-values');

0
...
2
-0
...
6
-0
...
8
0
...
4
0
...
2
-0
...
6
-0
...
8
0
...
4
0
...
2
-0
...
6
-0
...
5

0
...
5

-0
...
1:2*pi;
subplot(2,2,1);
plot(x,sin(x),'b*');
title('sin(x)')
subplot(2,2,2);
plot(x,cos(x),'r-o');
title('cos(x)')
subplot(2,2,3)
plot(x,exp(-x),'g
...
5

0
...
5

-0
...
5

0
...
5

0

0

2

4

6

8

-1

0

2

4

COLOR PLOTS

2D PLOTS
To plot with color and special symbols

2D PLOTS

2D PLOTS
To plot with color and special symbols
100
80
60

x = (-pi/2)+0
...
01:(pi/2)-0
...
5

-1

-0
...
5

1

1
...
01:pi;
plot(x,cos(x),'y-*');
title('This is cosine
function');
grid on

0
...
6
0
...
2
0
-0
...
4
-0
...
8
-1
-4

-3

-2

-1

0

1

2

3

4

2D PLOTS
To draw a circle with centre (1, 3)
Circle
5
4
...
5

y-axis

clc
clear all
t = linspace(0, 2*pi, 101);
x = 1 +2*cos(t);
y = 3 +2*sin(t);
plot(x,y,'r
...
5
2
1
...
5

-1

-0
...
5

1
x-axis

1
...
5

3

3
...
8

0
...
2
y axis

y = linspace(-10,10,1000)
plot(y,cos(y),'b
...
')
xlabel('x axis')
ylabel('y axis')
legend('cos(x)','cos(2x)‘)

0
...
2
-0
...
6
-0
...
1:5,-3:0
...
^2 + y
...
1:5,-3:0
...
^2 + y
...


You can change the domain by adding a second argument
to the call to ezplot
...
2

2
...
6

2
...
2

3
...
6

3
...

x 3 - 27 x
-40
-42
-44
-46

y=x^3-27*x;
ezplot(y,[2,4])
ylim([-60,-40])

-48
-50
-52
-54
-56
-58
-60

2

2
...
4

2
...
8

3
x

3
...
4

3
...
8

4

Note that you don’t have to define y first to use ezplot;
you can just type in the function you want to graph:
cos(2 x) cos(x)
1
0
...
6
0
...
2
0
-0
...
4
-0
...
8
-1
-6

-4

-2

0
x

2

4

6

POLAR PLOTS
90

1

120

60
0
...
6

150

30
0
...
2
180

0

210

330

240

300
270
r = cos(2 )

3D PLOTS
t=linspace(0,2*pi,500);
x=cos(t);
y=sin(t);
z=sin(5*t);
xlabel('x-axis');
ylabel('y-axis');
zlabel('z-axis');
title('3D Curve');
comet3(x,y,z);
plot3(x,y,z);

Curves in space
You can use the ”ezplot3” function to graph curves in
space
...
5

1
0
...
5
y

-0
...
2:2);
g = x
...
^2 - y
...
5

0

-0
...
05:1;
y=-1:
...
*y
...
^3
surf(x,y,z);
colormap spring
shading interp

1

0
...
5

-1
1
0
...
5

0

0

-0
...
5
-1

-1

3D PLOTS
2 x2 + 2 y2

syms x y
f = 2*(x^2+y^2)
ezsurf(f)
colormap cool

150

100

50

0
5
5
0

0
-5

y

-5
x

3D PLOTS

x 2+y 2

200

150

100

50

0
10

>> ezsurf('x^2+y^2',[10 10 -10 10])
>> ezsurf('x^2+y^2',[10 10 -10 10],'circ')

5

10
5

0

0

-5

-5
-10

y

-10

x

x 2+y 2

250
200

z

150
100
50
0
20
10

20
10

0

0

-10
y

-10
-20

-20

x

SAVE PLOTS



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