Post on 06-Apr-2018
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MATLAB - Introduction course
Fanilo RAMASOMANANA
Introduction course
MATLAB
ramasoma@unistra.fr
MATLAB - Introduction course
Context
What is MATLAB?
Objectives
Introduction to Chapter 1:
Starting and Quitting MATLAB
MATLAB Desktop
Desktop Tools
MATLAB - Introduction course
What is MATLAB?
MATLAB is a commercial software of interactive calculus. It makes it
possible to carry out numerical simulations based on algorithms of
numerical analysis. It can thus be used for solving numericalproblems for the approximate resolution of differential equations,
partial differential equations, linear and nonlinear systems, or
scientific and engineering graphics, etc and to write programs in a
lower level language.
MATLAB provides a block diagram tool for modeling and simulating
dynamical systems, including signal processing, controls,
communications, and other complex systems ranging from
engineering and mathematics to chemistry, biology, and economics.
MATLAB - Introduction course
Objectives
The objective of this MATLAB's course is double:
the knowledge of this software is essential because it is more
and more used for calculus in industries and banks,
the knowledge of algorithms existing in the software and to
test new algorithms.
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MATLAB - Introduction course
Introduction
This chapter provides a brief introduction to starting and
quitting MATLAB, and the tools and functions that help you to
work with MATLAB variables and files.
Chapter 1:
MATLAB - Introduction course
Starting and Quitting MATLAB
On a Microsoft Windows platform, to start MATLAB, double-
click the MATLAB shortcut icon on your Windows desktop.
Starting MATLAB:
Quitting MATLAB:
To end your MATLAB session, select Exit MATLAB from theFile menu in the desktop, or type quit in the Command
Window.
MATLAB - Introduction course
MATLAB Desktop
When you start MATLAB, the MATLAB desktop appears,containing tools for managing files, variables, and applications
associated with MATLAB.
The first time MATLAB starts, the desktop appears as shown
in the following illustration.
MATLAB - Introduction course
MATLAB Desktop
You can change the
way your desktop looks
by opening, closing,
moving, and resizing
the tools in it. You can
also move tools
outside of the desktop
or return them back
inside the desktop.
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MATLAB - Introduction course
Desktop Tools
This section provides an introduction to MATLABs desktop
tools. The tools are:
Command Window
Command History
Help Browser
Current Directory
Workspace
Array Editor
Create M-Files
MATLAB - Introduction course
Desktop Tools
Use the Command
Window to make
calculations and run
functions which exist
in MATLAB and M-
files (programs)
created by us.
Command Window:
MATLAB - Introduction course
Desktop tools
Lines you enter in theCommand Window
are logged in the
Command History
window. In the
Command History,
you can view
previously used
functions, and copyand execute selected
lines.
Command History:
MATLAB - Introduction course
Desktop tools
Use the Help browser to search and view documentation for all
MathWorks products. The Help browser is a Web browser
integrated into the MATLAB desktop that displays HTML
documents.
To open the Help browser, click the help button in the toolbar, or
type helpbrowser in the Command Window.
Help Browser:
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MATLAB - Introduction course
Desktop tools
Help Browser:
MATLAB - Introduction course
Desktop tools
Current Directory Browser:
MATLAB file operations
use the current directory as
reference points. Any file
you want to run must be in
the current directory.
To search for, view, open,
and make changes toMATLAB-related directories
and files, use the MATLAB
Current Directory browser.
MATLAB - Introduction course
Desktop tools
Workspace Browser:
The MATLAB workspaceconsists of the set of variables
(named arrays) built up during
a MATLAB session and stored
in memory. You add variables
to the workspace by using
functions, running M-files, and
loading saved workspaces.
To view the workspace and
information about eachvariable, use the Workspace
browser.
MATLAB - Introduction course
Desktop tools
Workspace Browser:
To delete variables from the workspace, select the variable and selectDelete from the Edit menu. Alternatively, use the clear all function. The
workspace is not maintained after you end the MATLAB session.
To save the workspace to a file that can be read during a later MATLAB
session, select Save Workspace As from the File menu, or use the
save function. This saves the workspace to a file called a MAT-file,
which has a .mat extension.
To read in a MAT-file, select Import Data from the File menu, or usethe load function.
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MATLAB - Introduction course
Desktop tools
Workspace Browser (Array Editor):
Double-click on a
variable in the
Workspace browser
to see it in the Array
Editor.
MATLAB - Introduction course
Desktop tools
Create M-Files:
To create M-files, select New M-files from the File menu,
which allow to write programs and run MATLAB functions.
We can save the new algorithms in a any directory in a file
called a M-file, which has a .m extension.
If you just need to view the contents of an M-file, you can
display it in the Command Window by using the name of
the function or running this function.
MATLAB - Introduction course
Chapter 2
Operators fornumbers
Special functions for numbers
Operators for vectors
Special functions for vectors
Operators for matrices
Special functions for matrices
MATLAB - Introduction course
Expressions for numbers
+ Addition
- Subtraction
* Multiplication
pi 3.1415
i Imaginary unit
Inf Infinity
NaN Not a numberabs Absolute value
Operators for numbers:
Special functions:
sqrt Square root
log Logarithm
exp Exponentiel
sign Signe of the number(=1 if positif and 0 if negatif)
/ Division^ Power
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MATLAB - Introduction course
Special functions
sin Sine in radians
sind Sine in degrees
asin Inverse of the function Sine in radians
asind Inverse of the function Sine in degrees
cos Cosine in radians
cosd Cosine in degrees
acos Inverse of the function Cosine in radians
acosd Inverse of the function Cosine in degreestan Tangent in radians
cot Cotangent in radians
Trigonometric functions:
MATLAB - Introduction course
Complex numbers
abs the magnitude of the complex number
angle the phase angle of the complex number
real the real part of the complex number
imag the imaginary part of the complex number
conj the conjugate of the complex number
special functions:
MATLAB - Introduction course
Vectors
V=[2,3,7] is a row vectorV=[2;3;7] is a column vector
V change the vector from line to column or from
column to line.
Create a vector:
Operators for vectors:
+ Addition
- Subtraction
* Scalar product.* Element by element multiplication
./ Element by element division
MATLAB - Introduction course
Vectors
X=1:10 is a row vector containing the integers from 1 to
10. By default the increment here is equal to 1.
For a nonunit spacing, we can specify an increment. For
example:
X=100:-7:50 or X=0:pi/4:pi
Colon operator (:)
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Vectors
Special functionsones(1,3) is a row vector all components is equal to 1.
ones(3,1) is a column vector all components is equal to 1.
zeros(1,3) is a row vector all components is equal to 0.
zeros(3,1) is a column vector all components is equal to 0.
rand(1,3) is a row vector with random components between
0 and 1.
sum(X) computes the sum of the elements of X.
find(X
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MATLAB - Introduction course
Matrices
Special functions
diag(A) computes the diagonal of A.
det(A) computes the determinant of A.
inv(A) computes the inverse of A.
eig(A) computes the eigenvalues of A.
poly(A) computes the coefficients of the characteristicpolynomial of A.
MATLAB - Introduction course
Graphics
Plot of the function Sine
x=0:pi/100:2*pi;
y=sin(x);
plot(x,y)
We can label the axes and add a title:
xlabel(x)ylabel(Sine of x)
title(Plot of the Sine function)
MATLAB - Introduction course
Graphics
Multiple data sets in one graph
x=0:pi/100:2*pi;
y1=sin(x); y2=sin(x-0.25); y3=sin(x-0.5);
plot(x,y1,x,y2,x,y3)
The legend command provides an easy way to identify the
individual plots:
legend(sin(x),sin(x-0.25),sin(x-0.5))
MATLAB - Introduction course
Graphics
Multiple data sets in one graph
We can also use this format:figure(1);
plot(x,y1);
hold on;
plot(x,y2);
hold on;
plot(x,y3);
legend(sin(x),sin(x-0.25),sin(x-0.5))hold off;
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Graphics
Controlling the axes
By default, MATLAB finds the maxima and the minima of
the data to choose the axis limits. The axis command
enables you to specify your own limits:
axis([xmin xmax ymin ymax])
Or for three-dimensional graph:
axis([xmin xmax ymin ymax zmin zmax])
MATLAB - Introduction course
Graphics
Multiple plots in one figure
The subplot command enables you to display multiple plots
in the same window or print them on the same piece of
paper. Typing: subplot(m,n,p)
partitions the figure window into an m-by-n matrix of small
subplots and selects the pth subplot for the current plot.
The plots are numbered along first the top row of the figurewindow, then the second row, and so on.
MATLAB - Introduction course
Graphics
Multiple plots in one figureExample:
subplot(2,2,1)plot(x,y1);
hold off;
subplot(2,2,2)
plot(x,y2);
hold off;
Subplot(2,2,3)
Plot(x,y3);
hold off;
subplot(2,2,4);plot(x,y4);
hold off;
MATLAB - Introduction course
Graphics
Saving a figure
To save a figure, select save from the file menu or click on
the save button of the figure.
The figure is then saved as a fig file.
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Chapter 3
Programming with MATLAB
if statements
for loops
while loops
MATLAB - Introduction course
Chapter 3
if
The if statement evaluates a logical expression and
executes a group of statements when the expression is
true. The optional elseif and else keywords provide for the
execution of alternate groups of statements.
An end keyword, which matches the if, terminates the last
group of statements. The groups of statements aredelineated by the four keywords no braces or brackets
are involved.
MATLAB - Introduction course
Chapter 3
if (example):
if a < 0
a = a+1;
elseif a == 0
a=0;
else
a=a;
end
MATLAB - Introduction course
Chapter 3
for
The for loop repeats a group of statements a fixed,predetermined number of times.
A matching end delineates the loop.
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MATLAB - Introduction course
Chapter 3
for (example):
for i = 1:10
a(i) = i;
end
MATLAB - Introduction course
Chapter 3
while
The while loop repeats a group of statements an indefinite
number of times under control of a logical conditions.
A matching end delineates the loop.
MATLAB - Introduction course
Chapter 3
while (example):
while i < 0
a = i +1;
end
MATLAB - Introduction course
Chapter 3
The logical operators in the tests:
Logical operator MATLAB Symboland &
or |
equal ==
not equal ~=
Less than
Less or equal to =