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CE 205-MATLAB For Civil Engineers Irfan Turk Fatih University, 2013-14

This document discusses MATLAB commands for plotting, matrices, and 3D plots. It begins with using colon operators to define and modify matrices, then discusses functions like zeros, ones, diag, eye for creating special matrices. Later sections cover plotting commands like plot, title, legend; subplots; polar plots; meshgrid and 3D plotting functions like surf, contour, mesh. Examples are provided for each concept.

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PratyushAgarwal
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37 views9 pages

CE 205-MATLAB For Civil Engineers Irfan Turk Fatih University, 2013-14

This document discusses MATLAB commands for plotting, matrices, and 3D plots. It begins with using colon operators to define and modify matrices, then discusses functions like zeros, ones, diag, eye for creating special matrices. Later sections cover plotting commands like plot, title, legend; subplots; polar plots; meshgrid and 3D plotting functions like surf, contour, mesh. Examples are provided for each concept.

Uploaded by

PratyushAgarwal
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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CE 205-MATLAB for Civil Engineers

Irfan Turk
Fatih University, 2013-14

Using the Colon Operator


Colon operator is very powerful to define new matrices

or modifying an existing matrix.


>>K=1:7
returns
K= 1 2 3 4 5 6 7 . Let us define M as 3 by 5 matrix as
below.
>>M=[1 2 3 4 5; 6 7 8 9 0; 1 2 3 4 5];
>>x=M(2,:)
returns
x=
67890

Using the Colon Operator


>>x=M(2:3,:)
x=
67890
1 23 45
>>y=M(1:2,4:5)
y=
45
90
>>M(end , end)
ans=
5

returns

returns

returns

Special Matrices
Function Done Work
Example
creates an m x m matrix of zeros(size can
zeros(m) be change .i.e zeros(m,n) )
zeros(2)=[0 0;0 0]
creates an m x m matrix of ones (size can
ones(m) be change .i.e ones(m,n) )
ones(3,3)=[1 1 1;1 1 1;1 1 1]
gets the diagonal elements of a twodiag(A) dimensional matrix A
A=[1 2;4 7]; diag(A)=[1 7]
creates an m x m identity matrix (size
eye(m) can be changed. i.e. eye(n,m) )
eye(3)=[1 0 0;0 1 0;0 0 1]

Plotting

0.8

graph of sin(x)

0.6
0.4
0.2

y label

clear all;
close all;
x=0:pi/100:2*pi;
y=sin(x);
plot(x,y)
title('This is title')
xlabel('x label')
ylabel('y label')
legend('graph of sin(x)')
grid on

This is title
1

0
-0.2
-0.4
-0.6
-0.8
-1

Creates figure as on the right side in an


m file.

x label

Figure 1: Output of the commands


from the left side.

Subplots

subplot(2,1,1)
plot(x,y1,x,y2,x,y3,x,y4)
title('First Plot')
xlabel('x label')
ylabel('y label')
legend('2*cos(x)','3*cos(x)'...
,'4*cos(x)','5*cos(x)')
subplot(2,1,2)
plot(A)
title('Second Plot')
xlabel('x label 2')
ylabel('y label 2')
legend('Graph of vector A')

First Plot

y label

2*cos(x)
3*cos(x)
4*cos(x)
5*cos(x)

-5

x label
Second Plot
6

y label 2

x=0:pi/100:2*pi;
y1=2*cos(x);
y2=3*cos(x);
y3=4*cos(x);
y4=5*cos(x);
A=[0+0i 1+2i 2+5i 3+4i];

4
Graph of vector A
2
0

0.5

1.5
x label 2

2.5

Figure 2: Output of the commands


from the left side in an m file.

Subplots with Polar Plotting


x=0:pi/100:2*pi;
r=5-5*sin(x);
y=5*cos(4*x);

120

90

subplot(1,2,2)
polar(x,y)

60

150

subplot(1,2,1)
polar(x,r,'r')

10

120
30

180

330
240

270

300

60

2.5

150

210

90

30

180

210

330
240

270

300

Figure 3: Output of the commands


from the left side in an m file.

Three Dimensional Plotting

z label

x=-2:0.2:2;
y=-2:0.2:2;
[X,Y]=meshgrid(x,y);
Z=X.*exp(-X.^2-Y.^2);
surf(X,Y,Z)
title('This is a 3-D')
xlabel('x label')
ylabel('y label')
zlabel('z label')
%legend('meshgrid function')

This is a 3-D

0.5

-0.5
2
1

2
1

-1
y label

-1
-2

-2

x label

Figure 4: Output of the commands


from the left side in an m file.

Some Commands for 3-D Plots


Function
plot3(x,y,z)
comet3(x,y,z)
mesh(x,y,z)
surf(x,y,z)
contour(x,y,z)
surfc(x,y,z)
pcolor(x,y,z)

Done Work
Creates a 3-D line plot
Generates an animation version of plot3
Creates a meshed surface plot
Similar to the mesh plot
Generates a contour plot
Plots a combined surface plot and contour plot
Creates a pseudo color plot

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