Download to read offline
![Variable Names
Variable Names
Variable names
Variable names ARE
ARE case sensitive
case sensitive
Variable names can contain up to 63 characters (as of MATLAB 6.5
Variable names can contain up to 63 characters (as of MATLAB 6.5
and newer). One can use
and newer). One can use namelengthmax
namelengthmax command to
command to
verify it.
verify it.
Variable names must start with a letter followed by letters, digits,
Variable names must start with a letter followed by letters, digits,
and underscores.
and underscores.
MATLAB variables are defined by assignment. There is no need to
MATLAB variables are defined by assignment. There is no need to
declare in advance the variables that we want to use or their type.
declare in advance the variables that we want to use or their type.
Example
Example
x=1;
x=1; % Define the scalar variable x
% Define the scalar variable x
y=[1 2 3]
y=[1 2 3] % row vector
% row vector
z=[1;2;3]
z=[1;2;3] % column vector
% column vector
A=[1 2 3;4 5 6;7 8 9]
A=[1 2 3;4 5 6;7 8 9] % 3x3 matrix
% 3x3 matrix
whos
whos % List of the variables defined
% List of the variables defined
Note: terminate statement with semicolon (;) to suppress output.
Note: terminate statement with semicolon (;) to suppress output.](https://image.slidesharecdn.com/matlabintro-250323125820-aec48da5/75/MatlabIntroduction-presentation-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx-7-2048.jpg)
![M-Files
M-Files
An
An M-file
M-file might be used as a
might be used as a script
script, i.e. file consist set
, i.e. file consist set
of statements
of statements
In additional, one use M-files to write
In additional, one use M-files to write function
function, in this
, in this
case the file starts with function definition like:
case the file starts with function definition like:
function y = f(x)
function y = f(x)
function [u,v] = f(x,y,z)
function [u,v] = f(x,y,z)
File name
File name and the
and the name of function
name of function in the file are
in the file are
usually
usually identical
identical, however while they are different,
, however while they are different,
MATLAB use file name to call function.
MATLAB use file name to call function.
If you add additional function in same M-file, it
If you add additional function in same M-file, it
considered sub-function and might be called from inside
considered sub-function and might be called from inside
the M-file only. Only the first function might be called
the M-file only. Only the first function might be called
from outside.
from outside.](https://image.slidesharecdn.com/matlabintro-250323125820-aec48da5/75/MatlabIntroduction-presentation-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx-22-2048.jpg)
![Saving Results
Saving Results
We can save all our results for future reference
We can save all our results for future reference.
.
The command
The command
diary
diary ‘
‘FileName'
FileName'
saves all output to command window into the FileName.txt file until
saves all output to command window into the FileName.txt file until
this option is turned off by the command
this option is turned off by the command
diary off
diary off
The following commands save & load the entire workspace
The following commands save & load the entire workspace
into the file 'MyMatFile.mat'
into the file 'MyMatFile.mat'
save 'MyMatFile'
save 'MyMatFile'
load 'MyMatFile'
load 'MyMatFile'
save 'x.mat' x
save 'x.mat' x %
% save a specific variable
save a specific variable
saving in ASCII format:
saving in ASCII format:
x = (-1:0.4:1)' ;
x = (-1:0.4:1)' ; y = sin(x*pi)
y = sin(x*pi)
var = [x y]
var = [x y] % double-column
% double-column
save 'my_sin.dat' -ASCII -double var
save 'my_sin.dat' -ASCII -double var %
%Save in 16-digit ASCII format
Save in 16-digit ASCII format](https://image.slidesharecdn.com/matlabintro-250323125820-aec48da5/75/MatlabIntroduction-presentation-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx-23-2048.jpg)
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- 1. 1 1 MATLAB PRIMER MATLAB PRIMER byMichael Medvinsky(2014) by Michael Medvinsky(2014)
- 2. MATLAB MATLAB MATLAB is aprogram for doing numerical computation. MATLAB is a program for doing numerical computation. It was originally designed for solving linear algebra type It was originally designed for solving linear algebra type problems using matrices. It problems using matrices. It’ ’s name is derived from s name is derived from MATrix LABoratory. MATrix LABoratory. MATLAB has since been expanded and now has built-in MATLAB has since been expanded and now has built-in functions for solving problems requiring data analysis, functions for solving problems requiring data analysis, signal processing, optimization, and several other types signal processing, optimization, and several other types of scientific computations. It also contains functions for of scientific computations. It also contains functions for 2-D and 3-D graphics and animation. 2-D and 3-D graphics and animation.
- 3. MATLAB MATLAB When you firstopen MATLAB, notice: When you first open MATLAB, notice: 1. 1. The The command window command window is where you'll give is where you'll give MATLAB its input and view its output. MATLAB its input and view its output. 2. 2. The The workspace workspace shows you all of your current shows you all of your current working variables and other objects. working variables and other objects. 3. 3. The The history history shows you all commands you used shows you all commands you used in CW. in CW. 4. 4. The The Editor Editor for MATLAB scripts (M-files) . To for MATLAB scripts (M-files) . To save & run the m-file type 'F5'. To open the save & run the m-file type 'F5'. To open the editor with a new or old m-file use the command editor with a new or old m-file use the command open open file_name file_name
- 4. MATLAB help MATLAB help Forhelp, command description etc use F1 or following For help, command description etc use F1 or following commands: commands: help help command_name command_name helpwin helpwin command_name command_name doc doc command_name command_name helpdesk helpdesk command_name command_name demo demo command_name command_name lookfor lookfor keyword keyword (search unknown command) (search unknown command) http://www.mathworks.com/support/ http://www.mathworks.com/support/ For example when running For example when running “ “help sin help sin” ” one get one get SIN Sine of argument in radians. SIN(X) is the sine of the elements of X. See also ASIN, SIND. Overloaded functions Reference page in Help browser doc sin
- 5. Some Useful commands SomeUseful commands what what List all m-files in current directory List all m-files in current directory dir/ls dir/ls List all files in current directory List all files in current directory type test type test Display test.m in command window Display test.m in command window delete test delete test Delete test.m Delete test.m cd/chdir cd/chdir Change directory Change directory pwd pwd Show current directory Show current directory which test which test Display directory path to Display directory path to ‘ ‘closest closest’ ’ test.m test.m who who List known variables List known variables whos whos List known variables plus their size List known variables plus their size clear clear Clear variables from workspace Clear variables from workspace clc clc Clear the command window Clear the command window
- 6. MATLAB & Matrices MATLAB& Matrices MATLAB treats all variables as matrices. For our MATLAB treats all variables as matrices. For our purposes a matrix can be thought of as an array, in fact, purposes a matrix can be thought of as an array, in fact, that is how it is stored. that is how it is stored. Vectors are special forms of matrices and contain only Vectors are special forms of matrices and contain only one row OR one column. one row OR one column. Scalars are matrices with only one row AND one column Scalars are matrices with only one row AND one column
- 7. Variable Names Variable Names Variablenames Variable names ARE ARE case sensitive case sensitive Variable names can contain up to 63 characters (as of MATLAB 6.5 Variable names can contain up to 63 characters (as of MATLAB 6.5 and newer). One can use and newer). One can use namelengthmax namelengthmax command to command to verify it. verify it. Variable names must start with a letter followed by letters, digits, Variable names must start with a letter followed by letters, digits, and underscores. and underscores. MATLAB variables are defined by assignment. There is no need to MATLAB variables are defined by assignment. There is no need to declare in advance the variables that we want to use or their type. declare in advance the variables that we want to use or their type. Example Example x=1; x=1; % Define the scalar variable x % Define the scalar variable x y=[1 2 3] y=[1 2 3] % row vector % row vector z=[1;2;3] z=[1;2;3] % column vector % column vector A=[1 2 3;4 5 6;7 8 9] A=[1 2 3;4 5 6;7 8 9] % 3x3 matrix % 3x3 matrix whos whos % List of the variables defined % List of the variables defined Note: terminate statement with semicolon (;) to suppress output. Note: terminate statement with semicolon (;) to suppress output.
- 8. Special Variables Special Variables ans ansDefault variable name for results Default variable name for results pi pi Value of Value of π π eps eps Smallest incremental number Smallest incremental number inf inf Infinity Infinity NaN NaN Not a number Not a number e.g. 0/0 e.g. 0/0 i,j,1i,1j i,j,1i,1j imaginary unit imaginary unit i, i, i.e. i.e. square root of -1 square root of -1 realmin realmin The smallest usable positive realnumber The smallest usable positive realnumber realmax realmax The largest usable positive real number The largest usable positive real number SpecialVars.m SpecialVars.m
- 9. Other symbols Other symbols >> >>prompt prompt . . . . . . continue statement on next line continue statement on next line , , separate statements and data separate statements and data % % start comment which ends at end of line start comment which ends at end of line ; ; (1) (1) suppress output suppress output (2) (2) used as a row separator in a matrix used as a row separator in a matrix : : specify range specify range
- 10. Relational Operators Relational Operators MATLABsupports six relational operators. MATLAB supports six relational operators. Less Than Less Than < < Less Than or Equal Less Than or Equal <= <= Greater Than Greater Than > > Greater Than or Equal Greater Than or Equal >= >= Equal To Equal To == == Not Equal To Not Equal To ~= ~=
- 11. Math & AssignmentOperators Math & Assignment Operators Power Power ^ ^ or or .^ .^ a^b a^b or or a.^b a.^b Multiplication Multiplication * * or or .* .* a*b a*b or or a.*b a.*b Division Division / / or or ./ ./ a/b a/b or or a./b a./b or or or or . . ba ba or or b.a b.a NOTE: NOTE: 56/8 = 856 56/8 = 856 - - (unary) (unary) + + (unary) (unary) Addition Addition + + a + b a + b Subtraction Subtraction - - a - b a - b Assignment Assignment = = a = b a = b (assign (assign b b to to a a) ) Operators.m Operators.m
- 12. MATLAB Logical Operators MATLABLogical Operators MATLAB supports five logical operators. MATLAB supports five logical operators. not/~ not/~ element wise/scalar logical NOT element wise/scalar logical NOT and/& and/&element wise logical AND element wise logical AND or or / | / | element wise logical OR element wise logical OR && && logical logical (short-circuit) AND (short-circuit) AND || || logical logical (short-circuit) AND (short-circuit) AND
- 13. Logical Functions Logical Functions MATLABalso supports some logical functions. MATLAB also supports some logical functions. xor xor (a, b) exclusive or (a, b) exclusive or any any(x) returns 1 if any element of x is nonzero (x) returns 1 if any element of x is nonzero all all(x) (x) returns 1 if all elements of x are returns 1 if all elements of x are nonzero nonzero isnan isnan(x) returns 1 at each NaN in x (x) returns 1 at each NaN in x isinf isinf(x) returns 1 at each infinity in x (x) returns 1 at each infinity in x finite finite(x) returns 1 at each finite value in x (x) returns 1 at each finite value in x find find(x) (x) find indices and values of non zero elements find indices and values of non zero elements
- 14. Some Matrix functions SomeMatrix functions zeros zeros(rows, cols) – create zero matrix (rows, cols) – create zero matrix rand rand(rows, cols) – generate random matrix (rows, cols) – generate random matrix ones ones(rows, cols) – matrix with 1 in all entries (rows, cols) – matrix with 1 in all entries eye eye (rows, cols) – identity matrix (rows, cols) – identity matrix sub2ind sub2ind, , ind2sub ind2sub indices manipulation indices manipulation
- 15. Extracting a Sub-Matrix Extractinga Sub-Matrix A portion of a matrix can be extracted and stored in a A portion of a matrix can be extracted and stored in a smaller matrix by specifying the names of both matrices smaller matrix by specifying the names of both matrices and the rows and columns to extract. The syntax is: and the rows and columns to extract. The syntax is: sub_matrix = matrix ( r1 : rn , c1 : cn ) ; sub_matrix = matrix ( r1 : rn , c1 : cn ) ; sub_matrix = matrix ( r1 : rn , : ) ; sub_matrix = matrix ( r1 : rn , : ) ; sub_matrix = matrix ( : , c1 : cn ) ; sub_matrix = matrix ( : , c1 : cn ) ; sub_matrix = matrix ( r1 : dr : rn , c1 : dc : cn ) ; sub_matrix = matrix ( r1 : dr : rn , c1 : dc : cn ) ; where where r1 r1 and and rn rn specify the beginning and ending rows specify the beginning and ending rows and and c1 c1 and and cn cn specify the beginning and ending specify the beginning and ending columns to be extracted to make the new matrix. columns to be extracted to make the new matrix. The terms The terms dr dr and and dc dc define spacing different than one. define spacing different than one. matrix.m matrix.m
- 16. “ “Continuous Continuous” ” functions functions Numerically, wecannot represent a general continuous function Numerically, we cannot represent a general continuous function (x,f(x)) because it requires handling infinite data (for each point in (x,f(x)) because it requires handling infinite data (for each point in the range, we need to keep f(x)). Instead, we represent a function the range, we need to keep f(x)). Instead, we represent a function by its values at a finite number of data points (x_i,f(x_i)), where the by its values at a finite number of data points (x_i,f(x_i)), where the series of points {x_i} is typically referred to as the sampling points or series of points {x_i} is typically referred to as the sampling points or the grid points. Accordingly, the "continuous" functions in Matlab the grid points. Accordingly, the "continuous" functions in Matlab accepts a vector of point {x_i} and return a vector of values {f(x_i)}. accepts a vector of point {x_i} and return a vector of values {f(x_i)}. Some functions Some functions sqrt sqrt log log cos/acos/sin/asin etc cos/acos/sin/asin etc exp - exponential exp - exponential abs abs sign sign norm norm sum sum prod - product prod - product
- 17. Plotting Plotting MATLAB will plotone vector vs. another. The first one will be treated MATLAB will plot one vector vs. another. The first one will be treated as the abscissa (or x) vector and the second as the ordinate (or y) as the abscissa (or x) vector and the second as the ordinate (or y) vector. The vectors have to be the same length. vector. The vectors have to be the same length. MATLAB will also plot a vector vs. its own index. The index will be MATLAB will also plot a vector vs. its own index. The index will be treated as the abscissa vector. Given a vector treated as the abscissa vector. Given a vector “ “time time” ” and a vector and a vector “ “dist dist” ” we could say: we could say: >> plot (time, dist) >> plot (time, dist) % plotting versus time % plotting versus time >> plot (time + i*dist) >> plot (time + i*dist) % plotting versus time % plotting versus time >> plot (dist) >> plot (dist) % plotting versus index % plotting versus index Sometime we want to see it with different colorline stile Sometime we want to see it with different colorline stile >> plot (time, dist, line_characteristics) >> plot (time, dist, line_characteristics) And sometime we want to plot few functions in graphs And sometime we want to plot few functions in graphs >> plot(…), hold, plot(…) >> plot(…), hold, plot(…) >> plot(t,d1,l_c1, t,d2, l_c2) >> plot(t,d1,l_c1, t,d2, l_c2) To split page to several axes check use To split page to several axes check use >> subplot (rows, cols, place) >> subplot (rows, cols, place)
- 19. Plotting Plotting There are commandsin MATLAB to "annotate" a plot to put on axis There are commands in MATLAB to "annotate" a plot to put on axis labels, titles, and legends. For example: labels, titles, and legends. For example: To put a label on the axes we would use: To put a label on the axes we would use: >> xlabel ('X-axis label') >> xlabel ('X-axis label') >> ylabel ('Y-axis label') >> ylabel ('Y-axis label') To put a title on the plot, we would use: To put a title on the plot, we would use: >> title ('Title of my plot') >> title ('Title of my plot') To distinct between function in the graph use: To distinct between function in the graph use: >> legend(legend_1, legend_2) >> legend(legend_1, legend_2) plotting.m plotting.m
- 20. Flow control (condition) Flowcontrol (condition) An if - elseif - else structure. (Note that elseif is An if - elseif - else structure. (Note that elseif is one one word) word) if if expression1 expression1 statements1 statements1 elseif elseif expression2 expression2 statements2 statements2 else else statements3 statements3 end end An switch-case structure An switch-case structure switch switch switch_expr switch_expr case case case_expr case_expr statement, ..., statement statement, ..., statement case case {case_expr1, case_expr2, case_expr3, ...} {case_expr1, case_expr2, case_expr3, ...} statement, ..., statement statement, ..., statement otherwise otherwise statement, ..., statement statement, ..., statement end end
- 21. Flow control (loops) Flowcontrol (loops) A for loop in MATLAB A for loop in MATLAB for for ind = 1:100 ind = 1:100 b(ind)=sin(ind/10) b(ind)=sin(ind/10) end end Alternative (Most of the loops can be avoided!!!): Alternative (Most of the loops can be avoided!!!): x=0.1:0.1:10; x=0.1:0.1:10; b=sin(x); b=sin(x); A while loop in A while loop in while while x <= 10 x <= 10 % execute these commands % execute these commands end end
- 22. M-Files M-Files An An M-file M-file mightbe used as a might be used as a script script, i.e. file consist set , i.e. file consist set of statements of statements In additional, one use M-files to write In additional, one use M-files to write function function, in this , in this case the file starts with function definition like: case the file starts with function definition like: function y = f(x) function y = f(x) function [u,v] = f(x,y,z) function [u,v] = f(x,y,z) File name File name and the and the name of function name of function in the file are in the file are usually usually identical identical, however while they are different, , however while they are different, MATLAB use file name to call function. MATLAB use file name to call function. If you add additional function in same M-file, it If you add additional function in same M-file, it considered sub-function and might be called from inside considered sub-function and might be called from inside the M-file only. Only the first function might be called the M-file only. Only the first function might be called from outside. from outside.
- 23. Saving Results Saving Results Wecan save all our results for future reference We can save all our results for future reference. . The command The command diary diary ‘ ‘FileName' FileName' saves all output to command window into the FileName.txt file until saves all output to command window into the FileName.txt file until this option is turned off by the command this option is turned off by the command diary off diary off The following commands save & load the entire workspace The following commands save & load the entire workspace into the file 'MyMatFile.mat' into the file 'MyMatFile.mat' save 'MyMatFile' save 'MyMatFile' load 'MyMatFile' load 'MyMatFile' save 'x.mat' x save 'x.mat' x % % save a specific variable save a specific variable saving in ASCII format: saving in ASCII format: x = (-1:0.4:1)' ; x = (-1:0.4:1)' ; y = sin(x*pi) y = sin(x*pi) var = [x y] var = [x y] % double-column % double-column save 'my_sin.dat' -ASCII -double var save 'my_sin.dat' -ASCII -double var % %Save in 16-digit ASCII format Save in 16-digit ASCII format
- 24. MATLAB also havehumor MATLAB also have humor why why % try this command % try this command
- 25.