MATLABfor Scientists and Engineers

Numerical Computingwith .

Byoung-Jo CHOI, PhDUniversity of Incheon

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References MATLAB Getting Started Guide, MathWorks

MATLAB User's Guide, MathWorks

Mastering MATLAB 7, Duane Hanselman and Bruce Littlefield, Pearson/Prentice Hall, 2005

Numerical Computing with MATLAB, Cleve Moler, MathWorks

임종수의 MATLAB7, 높이깊이 , 2009

MATLAB: An Introduction with Applications, Amos Gilat, John Wiley & Sons, Inc., 2004

Graphics and GUIs with MATLAB, 3rd Ed, Patrick Marchand and O. Thomas Holland, Chapman & Hall/CRC, 2003

Script M-Files

Numerical Computingwith .

MATLAB for Scientists and Engineers

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You will be able to

Write simple script m-files using the editor, Get user inputs and print the formatted results, Give explanations on your scripts using com-

ments, Use cell mode for efficient coding and evalua-

tion, Create a simple dialogue window, Save and Load data to/from MATLAB data file,

text file as well as Excel files Use timer to perform repeated action

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What is Script M-File

Text file comprised of a series of MATLAB commands

The file name ends with .m, hence m-file. MATLAB interprets the lines in a script m-file. Example

calc_price.mcalc_price.m

1:2:3:4:5:

1:2:3:4:5:

% Calculate the total pricenItem = input('Enter the number of items:');uPrice = input('Enter the unit price:');tPrice = nItem * uPrice;fprintf('The total price is %d.\n', tPrice );

% Calculate the total pricenItem = input('Enter the number of items:');uPrice = input('Enter the unit price:');tPrice = nItem * uPrice;fprintf('The total price is %d.\n', tPrice );

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Launching M-File Editor 1/3

'New M-File' Toolbar

Using ToolbarUsing Toolbar

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Launching M-File Editor 2/3

'File – New – M-File' Menubar

Using MenubarUsing Menubar

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Launching M-File Editor 3/3

From Command History Window Create m-file using the past commands

Popup MenuPopup Menu

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Save and Run the Script

F5 to save the changes and

run the entire script.

Run AllRun All

SaveSave

Modified but Not Saved Yet! Modified but Not Saved Yet!*

F5F5

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Evaluate the Selected Script

F9 to run the selected script. Menubar: Text – Evaluate Section

F9 to Run theF9 to Run the Selection Using Hot KeyUsing Hot Key

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Useful Functions for Scripts

For User Interactions

beepbeep

Echo MATLAB commands in scripts.Echo MATLAB commands in scripts.echo onecho on

echo offecho off Act silently. Default mode.Act silently. Default mode.

price = input('Enter the Unit Price: ');fprintf('The price is %d.\n', price * 20 );price = input('Enter the Unit Price: ');fprintf('The price is %d.\n', price * 20 );

name = input('Enter your name: ','s');disp(name);name = input('Enter your name: ','s');disp(name);

string input

number input

pausepause pause(5)pause(5)sec waitforbuttonpresswaitforbuttonpress

keyboardkeyboard Gives control to keyboard. Go into k>> modeType R-E-T-U-R-N (5 characters) to exit.

Gives control to keyboard. Go into k>> modeType R-E-T-U-R-N (5 characters) to exit.

Debug Mode

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Getting User Inputs 1/2

Getting user input from command linegreetings_input.mgreetings_input.m

% Get user inputs using command linename = input('Your name: ','s');age = input('Your age: ');fprintf( ['Hello, %s!' ... ' You will be %d years old next year\n'], ... name, age+1);%%fprintf( 'Press key to continue..');pausetoday1 = date;fprintf( '\nToday is %s.\n', today1 );

% Get user inputs using command linename = input('Your name: ','s');age = input('Your age: ');fprintf( ['Hello, %s!' ... ' You will be %d years old next year\n'], ... name, age+1);%%fprintf( 'Press key to continue..');pausetoday1 = date;fprintf( '\nToday is %s.\n', today1 );

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Getting User Inputs 2/2

Getting user input from dialog boxgreetings_dlg.mgreetings_dlg.m

%% Get user inputs using dialogprompt = {'Your name', 'Your age:'};dlg_title = 'Greetings';num_lines = 1;def = {'Sam','21'};answer = inputdlg (prompt,dlg_title,num_lines,def);name = answer{1};age = str2num (answer{2});msg = sprintf( 'Hello, %s! You will be %d years old next year\n', name, age+1);h = msgbox (msg, 'Greetings');uiwait (h)today1 = date;msg = sprintf( '\nToday is %s.\n', today1 );h = msgbox (msg, 'Greetings');

%% Get user inputs using dialogprompt = {'Your name', 'Your age:'};dlg_title = 'Greetings';num_lines = 1;def = {'Sam','21'};answer = inputdlg (prompt,dlg_title,num_lines,def);name = answer{1};age = str2num (answer{2});msg = sprintf( 'Hello, %s! You will be %d years old next year\n', name, age+1);h = msgbox (msg, 'Greetings');uiwait (h)today1 = date;msg = sprintf( '\nToday is %s.\n', today1 );h = msgbox (msg, 'Greetings');

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Other Dialog Boxes

various_dlgs.mvarious_dlgs.mwarndlgwarndlg

errordlgerrordlg helpdlghelpdlg

questdlgquestdlg

listdlglistdlg

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Comments

Line comments

Block comments

% This m-file demonstrates filtering operation% of FIR designed for removing a tone noise.% Refer to Book1 for the exact algorithm% Three 2-R plot will be drawn.

% This m-file demonstrates filtering operation% of FIR designed for removing a tone noise.% Refer to Book1 for the exact algorithm% Three 2-R plot will be drawn.

%{This m-file demonstrates filtering operationof FIR designed for removing a tone noise.Refer to Book1 for the exact algorithm}%

%{This m-file demonstrates filtering operationof FIR designed for removing a tone noise.Refer to Book1 for the exact algorithm}%

Useful for commenting out a block of code temporarily for debugging.

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Commenting Out

Ctrl+R for commenting out the selection Ctrl+T for un-commenting out the selection

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Code Cells

Code blocks separated by %%%% Initializing Data StructureFs = 1440; % Sampling frequencyTs = 1 / Fs; % Sampling TimeF0 = 2.4e3; % Carrier frequency

%% Generate Time Domain Signalt = 0:Ts:2;s = sin(2*pi*F0*t);

%% Plot the Signalplot(t,s);

%% Initializing Data StructureFs = 1440; % Sampling frequencyTs = 1 / Fs; % Sampling TimeF0 = 2.4e3; % Carrier frequency

%% Generate Time Domain Signalt = 0:Ts:2;s = sin(2*pi*F0*t);

%% Plot the Signalplot(t,s);

Code Cell 3

Code Cell 1

Code Cell 2

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Enabling Cell Mode

When enabled, cell control toolbar appears.

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Evaluating the Cells

Run / Run & Go

Evaluate the current cell.Evaluate the current cell.

Evaluate the cell and advance to the next cell.Evaluate the cell and advance to the next cell.

CtrlCtrl EnterEnter+

CtrlCtrl ShiftShift+ EnterEnter+

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Modify Parameter and Run the Cell

Increment / decrement a parameter by Multiply / divide a parameter by

Change the value near the

cursor and execute the cell.

Change the value near the

cursor and execute the cell.

plot_cosine.mplot_cosine.m

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Output Commands - disp

disp

disp(name of a variable) or disp('text as string')disp(name of a variable) or disp('text as string')

disp_demo.mdisp_demo.m

n = [8 1 6]disp(n) % show the values of ndisp('Magic Numbers') % just textdisp(['The numbers are: ' num2str(n)]) % text and No's

n = [8 1 6]disp(n) % show the values of ndisp('Magic Numbers') % just textdisp(['The numbers are: ' num2str(n)]) % text and No's

>> disp_demon = 8 1 6 8 1 6Magic NumbersThe numbers are: 8 1 6

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Output Commands – fprintf 1/4

fprintf

fprintf('text') or fprintf('format',arg1, arg2,..)fprintf('text') or fprintf('format',arg1, arg2,..)

fprintf_demo.mfprintf_demo.m

n = [8 1 6];fprintf( '%2d %2d %2d\n', n );fprintf('Magic Numbers\nDo Exist!\n') % just textfprintf('The numbers are %d, %d and %d.\n', n)

n = [8 1 6];fprintf( '%2d %2d %2d\n', n );fprintf('Magic Numbers\nDo Exist!\n') % just textfprintf('The numbers are %d, %d and %d.\n', n)

>> fprintf_demo 8 1 6Magic NumbersDo Exist!The numbers are 8, 1 and 6.

\n new line\t horizontal tab%d decimal integer%x hexadecimal%f floating point%*d field width, ..

\n new line\t horizontal tab%d decimal integer%x hexadecimal%f floating point%*d field width, ..

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Output Commands – fprintf 2/4

fprintf understands vectors and matrices 2x multiplication table

times2_table.mtimes2_table.m

n = (1:9)';times2 = [ 2*ones(9,1) n 2*n ];fprintf('%d x %d = %2d\n', times2')

n = (1:9)';times2 = [ 2*ones(9,1) n 2*n ];fprintf('%d x %d = %2d\n', times2')

>> times2_table2 x 1 = 22 x 2 = 42 x 3 = 62 x 4 = 82 x 5 = 102 x 6 = 122 x 7 = 142 x 8 = 162 x 9 = 18

>> times2'ans = 2 2 2 2 2 2 2 2 2 1 2 3 4 5 6 7 8 9 2 4 6 8 10 12 14 16 18

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Output Commands – fprintf 3/4

advanced formatting field width and precision

format_demo.mformat_demo.m

fprintf('%4d %d %5.1f %-5.1f %+5.1f\n', ... 2, 2, pi, pi, pi );fprintf('%4d %d %5.1f %-5.1f %+5.1f\n', ... -2, -2, -pi, -pi, -pi );

fprintf('%4d %d %5.1f %-5.1f %+5.1f\n', ... 2, 2, pi, pi, pi );fprintf('%4d %d %5.1f %-5.1f %+5.1f\n', ... -2, -2, -pi, -pi, -pi );

>> format_demo 2 2 3.1 3.1 +3.1 -2 -2 -3.1 -3.1 -3.1

22 22 33 .. 11 33 .. 11

-- 22 -- 22 -- 33 .. 11 -- 33 .. 11

++ 33 .. 11

-- 33 .. 11

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Output Commands – fprintf 4/4

Writing into a text file Steps:

times2_table_file.mtimes2_table_file.m

n = (1:9)';times2 = [ 2*ones(9,1) n 2*n ];fid = fopen('times2.txt','w');fprintf(fid, '%d x %d = %2d\n', times2');fclose(fid);

n = (1:9)';times2 = [ 2*ones(9,1) n 2*n ];fid = fopen('times2.txt','w');fprintf(fid, '%d x %d = %2d\n', times2');fclose(fid);

fopen() fprintf() fclose()

times2.txttimes2.txt

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MATLAB Data File

save and load into/from MATLAB data file save

load

save mydatasave mydata

save mydata var1 var2 ...save mydata var1 var2 ...

save mydata var3 -appendsave mydata var3 -append

save –ascii mydata.txt var1save –ascii mydata.txt var1

load mydataload mydata

load mydata.txtload mydata.txt

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Reading from Excel File 1/2

xlsread Interactive range selection

a = xlsread('simple.xlsx',-1)a = xlsread('simple.xlsx',-1)

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Reading from Excel File 2/2

xlsread Read the entire excel file

Read a range of data from the excel file

a = xlsread('simple.xlsx')a = xlsread('simple.xlsx')

a = xlsread('simple.xlsx','Sheet1','A3:B4')a = xlsread('simple.xlsx','Sheet1','A3:B4')

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Writing to Excel File

xlswrite Write data into an Excel file.

xlswrite_demo.mxlswrite_demo.m

% Excel write demo% Write to the first sheet beginning from A1xlswrite('magic.xlsx', magic(4));% Write to a new sheet, 'Magic5', beginning from A1xlswrite('magic.xlsx', magic(5), 'Magic5');% Write to 'Sheet2' beginning from A1xlswrite('magic.xlsx', magic(6), 2);% Write to 'Sheet3' beginning from B2xlswrite('magic.xlsx', magic(7), 3, 'B2');

% Excel write demo% Write to the first sheet beginning from A1xlswrite('magic.xlsx', magic(4));% Write to a new sheet, 'Magic5', beginning from A1xlswrite('magic.xlsx', magic(5), 'Magic5');% Write to 'Sheet2' beginning from A1xlswrite('magic.xlsx', magic(6), 2);% Write to 'Sheet3' beginning from B2xlswrite('magic.xlsx', magic(7), 3, 'B2');

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repeated_hello.mrepeated_hello.m

t = timer('TimerFcn','say_hello','StartDelay',2, 'ExecutionMode','fixedDelay','Period', 3);

t = timer('TimerFcn','say_hello','StartDelay',2, 'ExecutionMode','fixedDelay','Period', 3);

Timer

Repeated action using timer function

StartDelayPeriod Period Period

start(t)start(t)

stop(t)stop(t) delete(t)delete(t)

fixedRate fixedSpacingsingleShot

say_hello.msay_hello.m

function say_helloload voicessoundsc(hello,Fs)

function say_helloload voicessoundsc(hello,Fs) Try timer_demo.m!!Try timer_demo.m!!

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Timer Demo

A man says 'Hello!' repeatedly.timer_demo.mtimer_demo.m

% Timer demonstrationans = inputdlg('Period in seconds', ... 'Greeting Man Timer',1,{'3'});period = str2double(ans{1});t = timer('TimerFcn','say_hello','StartDelay',1, ... 'ExecutionMode','fixedDelay','Period', period);start(t);%% Listen to the voice for a while.h = msgbox('Do you want to stop the timer?' , ... 'Stop Timer');uiwait(h);stop(t)delete(t)

% Timer demonstrationans = inputdlg('Period in seconds', ... 'Greeting Man Timer',1,{'3'});period = str2double(ans{1});t = timer('TimerFcn','say_hello','StartDelay',1, ... 'ExecutionMode','fixedDelay','Period', period);start(t);%% Listen to the voice for a while.h = msgbox('Do you want to stop the timer?' , ... 'Stop Timer');uiwait(h);stop(t)delete(t)

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Start-up and Finish Script

User defined: startup.m, finish.m

matlabrc.mmatlabrc.m

pathdef.mpathdef.m

startup.mstartup.m

finish.mfinish.m

MATLAB

format compactcd c:\workformat compactcd c:\work

q='Sure?';b=questdlg(q,'Exit

Request','Yes','No','No');switch bcase 'No;

quit cancel;end

q='Sure?';b=questdlg(q,'Exit

Request','Yes','No','No');switch bcase 'No;

quit cancel;end

edit startupsav.medit startupsav.m

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Exercise 1 – Prime Factoring v1.0

Write a script file, 'ifactor.m', which gets a number from user and prints the number as a product of the prime factors. (Hint: factor)

>> ifactorPrime Factoring v1.0Enter a positive integer:3030 = 1 x 2 x 3 x 5>> ifactorPrime Factoring v1.0Enter a positive integer:4040 = 1 x 2 x 2 x 2 x 5

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Solution 1

Script

Screenshot of running 'ifactor'

ifactor.mifactor.m

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Exercise 2 – Prime Factoring v1.1

Write a script file, 'ifactor2.m', which gets a number from user using a dialog box and prints the number as a product of the prime factors at a message box.

[Hint: inputdlg(), msgbox()]

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Solution 2

Script and Screenshotifactor2.mifactor2.m

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Exercise 3 – Mean and Variance

Write a script file, 'icalc.m', which prints the mean and the variance of the data in 'mark-s.xlsx'.

[Hint: mean(), var()]

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Solution 3

Script

Screenshot of running icalc

icalc.micalc.m

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Notes

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Notes