Ch 3 Script M-Files

7/29/2019 Ch 3 Script M-Files

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MATLABfor Scientists and Engineers

Numerical Computing

with .

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 MATLAB7,, 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

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Script M-Files

Numerical Computing

with .

MATLABfor Scientists and Engineers


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You will be able to

Write simple scriptm-files using the editor, Get userinputs and print the formatted results,

Give explanations on your scripts using

comments,

Use cell mode for efficient coding and evaluation,

Create a simple dialoguewindow,

Save and Load data to/from MATLAB data file,

text file as well as Excel files

Use timerto perform repeated action

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What is Script M-File

Text file comprised of a series of MATLABcommands

The file name ends with .m, hence m-file.

MATLAB interprets the lines in a script m-file. Example

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calc_price.m

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 );


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Launching M-File Editor 1/3

'New M-File' Toolbar

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Using Toolbar


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'File

New

M-File' Menubar

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Using Menubar


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

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Popup Menu


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Save and Run the Script

F5 to save the changes andrun the entire script.

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Run All

Save

Modified butNot Saved Yet!*

F5


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Evaluate the Selected Script

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

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F9 to Run the Selection Using Hot Key


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Useful Functions for Scripts

For User Interactions

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beep

Echo MATLAB commands in scripts.echo on

echo off Act silently. Default mode.

price = input('Enter the Unit Price: ');

fprintf('The price is %d.\n', price * 20 );

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

disp(name);string input

number input

pause pause(5) sec waitforbuttonpress

keyboard Gives control to keyboard.

Go into k>> mode

Type 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 line

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greetings_input.m

% Get user inputs using command line

name = 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 box

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greetings_dlg.m

%% Get user inputs using dialog

prompt = {'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

14various_dlgs.m

warndlg

errordlg helpdlg

questdlg

listdlg


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Comments

Line comments

Block comments

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% 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}%

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 %%

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%% Initializing Data Structure

Fs = 1440; % Sampling frequency

Ts = 1 / Fs; % Sampling Time

F0 = 2.4e3; % Carrier frequency

%% Generate Time Domain Signal

t = 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

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Evaluate the current cell.

Evaluate the cell and advance to the next cell.

Ctrl Enter+

Ctrl Shift+ Enter+


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Modify Parameter and Run the Cell

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

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Change the value near the

cursor and execute the cell.

plot_cosine.m


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Output Commands - disp

disp

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

disp_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

>> disp_demo

n = 8 1 68 1 6

Magic NumbersThe numbers are: 8 1 6


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Output Commands fprintf 1/4

fprintf

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

fprintf_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)

>> 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, ..


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fprintf understands vectors and matrices 2x multiplication table

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times2_table.m

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 21 2 3 4 5 6 7 8 92 4 6 8 10 12 14 16 18


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advanced formatting field width and precision

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format_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 );

>> format_demo

2 2 3.1 3.1 +3.1-2 -2 -3.1 -3.1 -3.1

2 2 3 . 1 3 . 1

- 2 - 2 - 3 . 1 - 3 . 1

+ 3 . 1

- 3 . 1


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Writing into a text file Steps:

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times2_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);

fopen() fprintf() fclose()

times2.txt


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MATLAB Data File

save and load into/from MATLAB data file save

load

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save mydata

save mydata var1 var2 ...

save mydata var3 -append

saveascii mydata.txt var1

loadmydata

loadmydata.txt


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Reading from Excel File 1/2

xlsread Interactive range selection

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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

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a = xlsread('simple.xlsx')

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


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Writing to Excel File

xlswrite Write data into an Excel file.

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xlswrite_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 A1

xlswrite('magic.xlsx',magic(6), 2);

% Write to 'Sheet3' beginning from B2xlswrite('magic.xlsx',magic(7), 3, 'B2');


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repeated_hello.m

t = timer('TimerFcn','say_hello','StartDelay',2,

'ExecutionMode','fixedDelay','Period', 3);

Timer

Repeated action using timer function

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StartDelay

Period Period Period

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

fixedRate fixedSpacingsingleShot

say_hello.m

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


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Timer Demo

A man says 'Hello!' repeatedly.

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timer_demo.m

% Timer demonstration

ans = 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

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matlabrc.m

pathdef.m

startup.m

finish.m

MATLAB

format compact

cd c:\work

q='Sure?';

b=questdlg(q,'Exit

Request','Yes','No','No');

switch bcase 'No;

quit cancel;

endedit startupsav.m


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Exercise 1 Prime Factoring v1.0

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

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

Enter a positive integer:4040 = 1 x 2 x 2 x 2 x 5


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Solution 1

Script

Screenshot of running 'ifactor'

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ifactor.m


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Exercise 2 Prime Factoring v1.1

Write a script file, 'ifactor2.m', which gets anumber 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 Screenshot

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ifactor2.m


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Exercise 3 Mean and Variance

Write a script file, 'icalc.m', which prints themean and the variance of the data in

'marks.xlsx'.

[Hint: mean(), var()]

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Solution 3

Script

Screenshot of running icalc

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icalc.m


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Notes

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Notes

Documents

Ch 3 Script M-Files