04. m-file part1

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M- FILES

SCRIPT AND FUNCTION FILES

WHAT IS M-FILE?

An m-file, is a simple text file where you can

place Matlab commands. When the file is run,

Matlab reads the commands and executes them

exactly as it would if you had typed each

command sequentially at the Matlab prompt.

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Create, save, open

To create an m-file, choose Newfrom the Filemenuand select m-file. This procedure brings up a texteditor window in which you can enter Matlabcommands.

To save the m-file, simply go to the Filemenu andchoose Save (remember to save it with the '.m'extension).

To open an existing m-file, go to the File menu andchoose Open .

Running an m-file

After the m-file is saved with the name

filename.m in the Matlab folder or directory, you

can execute the commands in the m-file by

simply typing filename at the Matlab prompt.

If you don't want to run the whole m-file, you

can just copy the part of m-file that you want to

run and paste it at the Matlab prompt.

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SCRIPT FILES

Scripts are the simplest kind of program filebecause they have no input or output

arguments. They are useful for automating series

of MATLAB commands, such as computations

that you have to perform repeatedly from the

command line.

MATLAB m-filesScript Files

On the command line

>>x=3.0;

>>y=x^2;

>>y

y =

9.0

>>

In the script file named test.m

On the command line

>>test

y =

9.0

>>

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MATLAB m-files

Script Files

script files share the workspace memory

>>x=5.0;

>>test

>>y

y =

25.0

>>

test.m script

Function files

The main difference between a script and a function isthat a function accepts input from and returns outputto its caller, whereas scripts do not. You defineMATLAB functions in a file that begins with a linecontaining the function key word. You cannot define afunction within a script file or at the MATLABcommand line.

Functions always begin with a function definition lineand end either with the first matching end statement,the occurrence of another function definition line, orthe end of the file, whichever comes first. Using end tomark the end of a function definition is required onlywhen the function being defined contains one or morenested functions.

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MATLAB m-files

Function Files

Matlab identifies function files from script files by using the

function and return keywords

the name of the function file must be the same

name as the function

The function file x2.m

MATLAB m-filesFunction Files

>>r=3;

>>d=x2(r);

>>d

d =

9.0

>>

>>h=x2(4.2);

>>h

h =

17.64

>>

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MATLAB m-files

Function Files

Multiple Inputs and Outputs

outputs in square brackets, [ ] inputs in parentheses ( )

MATLAB Flow Controlexample

script file to cycle through x values

function file to generate the y values

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MATLAB Plotting

Basic 2D plotting functions

plot(x1,y1[,x2,y2,x3,y3.....])

xlabel(x axis name)

ylabel(y axis name)

title(graph name)

Additional functions

grid on

grid off

axis([xmin,xmax,ymin,ymax])

MATLAB Plottingexample y = sin(t)

the plot function alone

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script file to generate agraph of y = sin(t)

function file to generate a

graph of y = sin(t)

>>graphsin

>>


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M

FILE PART 1

EXERCISE NO. 04

M-file part1

Use m-file to compute the ff functions

x = t sin(t)

y = (t-1) / (t+1)

z = sin(t^2) / (t^2)

Create an m-file that will compute for the slope

of a straight line having your x and yintercept

as constants.

04. m-file part1

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