Beginning Programming in MATLAB

5/19/2018 Beginning Programming in MATLAB

1/17

Beginning Programming in

MATLAB

MAM1043H


2/17

What we know so far?

Can do some basi math !+,-,*,/,^"

#now how to set $% arra&s'(etors $sing a

o)on o%erator !x=1:10

" P)ot gra%hs !plot(x,y)"

*ome basi f$ntions !sin(), log()+++"


3/17

,s that not a)) we need??

- .or the sim%)est %rob)ems/ &es

B$t+++ its basia))& no different to $sing a

a)$)ator

- More om%)e2 a)$)ations re$ire more

ste%s+

Command )ine beomes tedio$s

Key Idea:

Can enter exactly any MATLAB commands in a

script file (called a m-file) and rn it from

t!e command line"


4/17

How do we do this?

- Create a new mfi)e5 !File\New\M-File"

MATLAB sri%t editor o%ens+

- T&%e in an& (a)id MATLAB statements+- *a(e the fi)e !eg+ m&test+m"

- 6$n the mfi)e from the ommand window

>>mytest

Mst #e "m7


5/17

A 8er& *im%)e 92am%)e

Create the mfi)e

92e$te the mfi)e


6/17

Creating o$r own f$ntions

- :sing mfi)es a))ows $s to reate o$r own

f$ntions+

- B$t+++ we need to reinter%ret what we

think of as f$ntions+


7/17

;B)ak Bo27 .$ntions

- Think of f$ntions as a ;b)ak bo27 that

%erforms some o%eration5

ffx y=f(x)

The o$t%$t (ariab)e

of the f$ntion5 ;y7

The in%$t (ariab)e!s" to

the f$ntion5 ;x7

The f$ntion

name5 ;f()7

The at$a) a)$)ation is %erformed inside

the b)ak bo2+++


8/17

The Anatom& of a .$ntion mfi)e

A f$ntion mfi)e is

identified with

;fnction7 on the

first )ine

The o$t%$t (ariab)e

of the f$ntion5 ;y7

The f$ntion

name5 ;f()7

The in%$t

(ariab)e!s" to the

f$ntion5 ;x7

The a)$)ation of the o$t%$t (ariab)e/

de%ending on the in%$t (ariab)e!s"

*a(e mfi)e as

;f"m7


9/17

.$ntion mfi)es

- Muststart with functionon the first)ine+

- Mustha(e at )east one o$t%$t (ariab)e+

- Mustha(e a $ni$e name+- Mustsa(e the mfi)e as the f$ntion name+

- Mustassign a (a)$e to the o$t%$t (ariab)e+

We will see some examples soon


10/17

6e%eating *tatements

- s method5xn+!

=xn-f(x

n)/f&(x

n)


11/17

The for Loo%

- 'ne of te waysof re%eating statements

is b& a for )oo%+

- *tr$t$re5

for x = Ni:Nf

...

Statements

end;

The inde2ing (ariab)e

*tarting (a)$e

9nding (a)$e

The statements to be

re%eated


12/17

.or Loo% 92am%)es

example$%"m

for n=1:5 y=n^2;

disp(y);

end;

example$%"m

for n=1:5 y=n^2;

disp(y);

end;

is%)a&s the s$aresfrom 1 to @

example$&"m

N = 5;S = 0;

for n=1:N

S = S + n^2;

end;

disp('SUM =');

disp(S)

example$&"m

N = 5;S = 0;

for n=1:N

S = S + n^2;

end;

disp('SUM =');

disp(S)

Ca)$)ates the s$m of n

from 1 to @

=eed to kee% adding n

to the s$m/ stored in *

example$'"m

N = 5;F = 1;

for n=1:N

F = F*n;

end;

example$'"m

N = 5;F = 1;

for n=1:N

F = F*n;

end;

Ca)$)ates @


13/17

Making a .atoria) .$ntion

.$ntion to a)$)ate =

Bt is t!ere is a pro#lem it! t!is

*!at a#ot $+


14/17

The .ibonai *e$ene

Let $s a)$)ate the .ibonai n$mbers5

0/1/1//3/@//13/1/ DE

The eah n$mber in the se$ene is

defined as the s$m of the %re(io$s two

n$mbers5

f)= f)-!+ f)-"


15/17

The .ibonai *e$ene

We wi)) store the n$mbers in a etorf

We a)so know the first two e)ements5

f=[0 1]; *o we nowterms 1 and / we need to

start a)$)ating from the 3rdterm+

,n MATLAB/ we wo$)d $se5 f(k)=f(k-1)+f(k-2);

The kth

term of the (etor


16/17

The .ibonai *e$ene


17/17

*ti)) to ome

How an we so)(e )inear s&stem of

e$ations?

Making deisions and )ogia) o%erations+

=$meria))& so)(ing differentia) e$ations+

Beginning Programming in MATLAB

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