MATLAB

Programming

By : Ahmed Moawad

LET’S BEGIN……

MATLAB is a tool that simplify the programming than

any other programming language like c , c# , …….

Let’s begin with first function in MATLAB …

And the most helpful Fn .

>> help ;

this function gives you a very useful tutorial ,

and information about using MATLAB in every

applications.

1

FIRST TIME : HOW TO INPUT A MATRIX OR

VECTOR IN MATLAB

Vector :

>> x = [1 2 3 4]

x = 1 2 3 4

o Matrix :

>> y = [1 2 3 ; 5 1 4 ; 2 3 1]

y = 1 2 3

5 1 4

2 3 1

2

CHARACTERISTICS OF MATRIX

Transpose :

>> xt = x ’ convert the columns to rows and vice versa

x = 1

2

3

4

>> x = [1 : 5]

x = 1 2 3 4 5 this is the step of increment

>>x = [1 : 2 : 5]

x = 1 3 5 3

CONTINUE……

>>size (y) Number of columns and rows

>>length(y) The tallest dimension(row , column) of Matrix

>>z = y( 2 , 2:3 ) Choose the second & third columns.

z = 1 4 Choose the second row.

>>zeros(M ,N); Matrix consists of zeros

>>ones(M,N); Matrix consists of ones

>>eye(M,N) ; The main diameter of Matrix is ones , others zeros

>>rand (M,N) ; Uniform Distribution

>>randn (M,N); Normally Disribution

1

5

4

OPERATORS

Scalar Arithmetic Operations :

>> z = x * y; multiply every element in x to its corresponding in y.

Matrices Arithmetic Operations:

>> z = x .* y ; multiply as matrices rules ,with condition (Num. of rows

of x = Num. of columns of y)

+ .+ Summation

- .- Subtraction

/ ./ Division

^ .^ Exponential

5

FUNCTIONS BREAK (1):

>>sign(x) ; If an element in matrix x is +ve returns 1 ,-ve returns

-1.

>>exp (2) The exponential function.

ans = 7.3891

round (x); Approximate the number x to the nearest number

Fix (x) ; Delete the fraction (1.2>>1, 1.6 >>1)

Abs(complex ); Magnitude of complex number

Angle(comp.); Angle of complex number

Real(complex); Real part of complex.

isprime(x) ; 0 for not , 1 for prime number

6

FLOW CONTROL FUNCTIONS

For loop:

i.e.:

>>a=3; initial value of b

>>for i = 1 :1: 10; initial : step : final

a=a +i;

end

>> disp(a); Fn. that display the value of a

>>sprintf (‘the number of icons is = %g ’ , a)

print the sentence ‘ ’ , replaces the %g by a

7

CONTINUE …. While loop:

i.e.:

>>b =0; initial value of b

>>while b<4 carry out if b <4 , stop if else

b=b+1;

end

>>weight = b*2.2;

>>disp(b);

>>sprintf(‘The weight equals %f ’ , weight)

weight is float type8

CONTINUE ….. If Statement:

i.e.:

degree =input(‘please insert the degree(0-100): ’)

fn. that make user input the value which preferred

if degree>= 85

disp(‘Excellent’)

elseif( degree>= 75 & degree <85)

disp(‘very good’)

elseif( degree>= 65 & degree <75)

disp(‘good’)

elseif( degree>= 50 & degree <65)

disp(‘pass’)

else

disp(‘fail’)

end 9

CONTINUE …… Switch …case:

i.e.:

month= input (‘please input the month(1-12): ’)

switch month

case { 1,3,5,7,8,10,12} more than one case>> {1,2,…..}

disp (31)

case{4 , 6 ,9 ,11}

disp (30)

case 2 only one case>> 1

disp (28)

end10

FUNCTION BREAK(2):

>>Str = ‘ the sentence you want to write’

>>w = str [ 1 2 5 7 9]

w = thsne

x(2) = 4 change the second element value in the matrix x to 4.

X(3) = [ ] delete the third element .

mean(x) The mean of elements of x .

std(x) The standard diversion of elements of x.

[theta phi r ] = cart2sph [2 , 3 , 5]

any names indicates the sph. Conversion fn. the values of Cartesian coordinates

11

GRAPHS

Line plot :

i.e.:

>>t = [ 0 : 10 ];

>> y = sin(t); y is sinusoidal wave on t

>>Figure(1) Open figure , name it 1

>>plot (t,y) plot t(h-axis) versus y (v-axis) in figure.

>>xlabel(‘time’) write 9time) under h-axis

>>ylabel(‘input’) write (input) beside v-axis

>>title (‘Gain’) Make a title for plot

12

CONTINUE …. Bar Graph:

i.e.:

>>x = -3 : 1 : 3;

>>y = x.^2;

>>bar(x,y) Bar Graph

>>figure(1)

>>subplot 221 divide the figure into number of plots

>>z= magic (3); special function

>>subplot 222 row no. column no. position

>>bar(z)

>>subplot (2,2,3)

>> bar(z , ‘grouped’) Style type

>>subplot(2,2,4)

>>bar (z , ‘stacked’)13

CONTINUE ….. Histogram :

>> hist (z , 7 ) Number of intervals in histogram

Pie Graph :

>>z = [10 4 5 8 2];

>>pie(z)

Polar Graph :

>>polar(t , y)

14

CONTINUE …… Scatter plot :

>>x =[1:10];

>> y = 2.*rand (1,10)

>>subplot 221

>>scatter(x ,y) scatter points on plot

>>subplot 222

>> stem ( x , y) scatter points connected with the h-axis

>>subplot 223

>>scatter(x ,y , 3 , ‘y’ ) Mark color (yellow)

size of mark (scatter point)15

CONTINUE …….

Pie graph Polar graph Bar graph

Histogramscatter graph 16

FUNCTION BREAK(3)

>>log (x) Ln Function

>>log10(x) Log. Decimal Function

>>log2 (x) Log. Binary Function

>>semilogy(x,y) convert v-axis to dB

>>semilogx(x,y) convert h-axis to dB

>>loglog(x,y) convert two axes to dB

>>barh(z) Opposite of Bar graph

>>break; stop loop and move to the next command

>>continue; stop the itertion and move to the other itertion on loop

>>surf(x,y,z) Graph the surface and put the points on it

>>contour(x,y,z) 17

SYMBOLIC MATH :

Functions: >>syms x y z ; convert this variables into symbols

>>f = x^2 + y^2 +z^2;

Substitution the symbols you want substitute

>>f1 = subs( f , [x y] , [4 5] ) the values of substitution

f1 = 16 + 25+z^2

Differentiation

>>f2 = diff ( f , 2 , z ) The symbol you want to diff.

f2 = 2 The order of diff.

Integration

>>f3 = int (f1 , -10 , 10 ) Final limit

f3 = 5 initial limit

Limit Fn

>>limit ( sin (x) /x , inf ) the value the limit approximate to

Summation

>>symsum( 1 / x^2 , 1 , inf ) the final sub . of summation

the initial sub. of summation18

DOMAINS TRANSFORMS :

Laplace Transform :

>>syms t ;

>> laplace ( cos (t)) laplace transform

Ans = s / (s^2 +1)

>>ilaplace (s/ (s^2 +1) inverse laplace transform

Ans = cos t

>>transferfn = tf ([1] , [1 2 1]) transfer fn.

Transfer function = 1 / s^2 + 2* s + 1

>> bode(transferfn) Bode plot

>> step(transferfn) Step response

>> impulse (transferfn) Impulse response19

CONTINUE …. Fourier Transform :

>>syms t w b ;

>>y = cos(b*t);

>> f = fourier (x , t ,w );

>>y = cos( 2*pi *t);

>>fd = fft ( y , 512 );

must be 2^n

20

THANK YOU