Basic of octave matlab programming language

BASICS OF OCTAVE/MATLAB
PROGRAMMING LANGUAGE
AULIA KHALQILLAH, S.SI
“Be thankful”
sharing.auliakhalqillah.com

INTRODUCTION
The OCTAVE and MATLAB is the one of the most programming language. It is simple to
learn about the language. The main of these programming language is to visualization
the data become a graph.
There are no big different between OCTAVE and MATLAB. However, the MATLAB has
more complete function compared to OCTAVE.
Also, OCTAVE is OPEN SOURCE software
https://www.gnu.org/software/octave/ https://www.mathworks.com/videos/programming-with-matlab-
86354.html

INTRODUCTION
In OCTAVE and MATLAB have 4 panels, such as:
 Command Window
 Workspace = The whole variables will be store in the workspace
 Current Folder = The active directory
 Text Editor = To write full script (like atom, notepad++, Xcode, etc)
In this note, we will use the command window to write the basic code of
OCTAVE/MATLAB programming language. After the all of the basic
code has been understood, we will explain how to write the full code
using the OCTAVE/MATLAB programming language.

USING COMMAND WINDOW:
VARIABLE
You can type the command bellow in your Command Window:
>> 5
ans = 5
When you type the command above, the output is ans = 5. The ans is name of
variable what you typed before. If you type as the command bellow:
>> x = 5
x = 5
The x is the new name of variable what you typed.

VARIABLE
If you add the (;) in the end of variable
>> x = 5;
The output variable doesn’t appear in the Command Window and it will
be stored in the Workspace

OPERATION OF MATH
The simple operation of math in OCTAVE/MATLAB programming
language is as follows:
>> x = 5;
>> y = 10;
>> z = x + y
z = 15
Operation Symbol
add +
substraction -
multiplication *
division /

CONSTANTS
In the OCTAVE/MATLAB programming language has a predefined
constants, such as:
Symbol Syntax information
𝜋 pi pi = 3.1416...
Imaginary i atau j 0 + 1i
epsilon eps 2.2204e-16
Infinity inf unlimited
- NaN no value
comment % to write some note in the code

FUNCTION OF MATH
In the OCTAVE/MATLAB programming language has a predefined
function, such as:
Symbol Syntax
sin x sin(x)
cos x cos(x)
arcsin x asin(x)
arccos x acos(x)
ex exp(x)
log10 x log10(x)
log2 x log2(x)
𝑥 sqrt(x)

FUCNTION OF MATH
Example
>> x = pi/2;
>> sin(x)
ans = 1
>> cos(x)
ans = 6.1232e-17
>> asin(x)
ans = 1.5708 - 1.0232i
>> acos(x)
ans = 0.00000 + 1.02323i
Example
>> exp(x)
ans = 4.8105
>> log10(x)
ans = 0.19612
>> log2(x)
ans = 0.65150
>> sqrt(x)
ans = 1.2533
>> log10(sin(x))
ans = 0

VECTOR
>> x = [1 2] % Term 1
x =
1 2
>> x = [1;2] % Term 2
x =
1
2
Term 1 have the output horizontally or as the row
Term 2 have the output vertically or as the column

VECTOR
If you want to make the vector (e.g. 1, 2, 3, ...., etc), you can type the command
as follows:
>> x = [1 2 3 4 5 6 7 8 9 10] % Row vector
x =
1 2 3 4 5 6 7 8 9 10
>> x = [1;2;3;4;5] % Column vector
x =
1
2
3
4
5

VECTOR
You can generate the vector using linspace
Term 1 => x = linspace(start, end)
>> x = linspace(1,2);
The vector will be start from 1 to 2 with the default of data length is 100. This
output will be as a row vector. To produce the column vector, you can type:
>> x = linspace(1,2)’;
The output will be stored in Workspace

VECTOR
The another term of linspace is:
Term 2 => linspace(start, end, N)
>> x = linspace(1,2,10);
The vector will be start from 1 to 2 with length of data is 10.
The another one term to generate the vector:
Term 3 => x = start:end
>> x = 1:10
x =
1 2 3 4 5 6 7 8 9 10

VECTOR
Term 4=> x = start:step:end
>> x = 1:2:20
x =
1 3 5 7 9 11 13 15 17 19

FUNCTION AND OPERATION OF VECTOR
Symbol Syntax Information
ak a(k) The component k-th of vector a
an a(end) The last component of vector a
𝑎 =
𝑘=1
𝑛
𝑎 𝑘
1/2
norm(a) normalization of vector
ab a*b multiplication of vector
max{ak}k=1, .. n max(a) maximum value of vector a
max{ak}k=1, .. N min(a) minimum value of vector a
n(a) length(a) size of vector a
𝑘=1
𝑛
𝑎 𝑘
sum(a) The summation of vector a
𝑘=1
𝑛
𝑎 𝑘
prod(a) The multiplication of vector a

FUNCTION AND OPERATION OF VECTOR
Symbol Syntax Information
𝑘=1
𝑛
𝑎 𝑘 𝑏 𝑘
dot(a,b) dot product between vector a and b
(a1b1, ....., anbn) a.*b multiplication between components
Example:
>> x = [3 2 5];
>> y = [4 1 6];
>> length(x)
ans = 3
>> length(y)
ans = 3
Example:
>> norm(x)
ans = 6.1644
>> dot(x,y)
ans = 44
>> z = x.*y
z =
12 2 30
Example
>> max(x)
ans = 5
>> max(y)
ans = 6

MATRIX
To produce the matrix, you can type:
>> x = [1 2 3;4 5 6;7 8 9]
x =
1 2 3
4 5 6
7 8 9
The output is the example of matrix with size 3 x 3. The sign of (;) as the new
row for the matrix.

MATRIX
INDEX OF MATRIX
Columns
𝐴 =
𝑎1 𝑎2 𝑎3
𝑎4 𝑎5 𝑎6
𝑎7 𝑎9 𝑎10
Rows
In OCTAVE/MATLAB index of matrix can be written as A(i,j), where the i
as the row and j as the column

MATRIX
EXAMPLE
>> A = [1 2 3;4 5 6;7 8 9]
A =
1 2 3
4 5 6
7 8 9
If you want to take the element
from the third row and the second
column of the matrix A, you can
type:
>> AA = A(3,2)
AA = 8
EXAMPLE
>> A = [1 2 3;4 5 6;7 8 9]
A =
1 2 3
4 5 6
7 8 9
If you want to take the
element from the first column,
you can type:
>> AA = A(:,1)
AA =
1
4
7

PENGGUNAAN COMMAND WINDOW:
MATRIKS
EXAMPLE
>> A = [1 2 3;4 5 6;7 8 9]
A =
1 2 3
4 5 6
7 8 9
element from first row and
second row, you can type:
>> AA = A(1:2,:)
AA =
1 2 3
4 5 6
EXAMPLE
>> A = [1 2 3;4 5 6;7 8 9]
A =
1 2 3
4 5 6
7 8 9
element second column and
third column, you can type:
>> AA = A(:,2:3)
AA =
2 3
5 6
8 9

MATRIX OPERATION
The operation of math in matrix as follows:
 ADDITION (+),
 SUBSTRACTION(-),
 MULTIPLICATION (*),
 MULTIPLICATION BETWEEN ELEMENT(.*),
 POWER (^),
 TRANSPOSE (‘),
 LEFT DIVISION (),
 RIGHT DIVISION (/).
EXAMPLE
>> A = [1 2 3;4 5 6;7 8 9];
>> B = [2 4 6;8 10 12; 1 2 3];
>> C = A+B % Add
C =
3 6 9
12 15 18
8 10 12
>> C = A-B % Substrac
C =
-1 -2 -3
-4 -5 -6
6 6 6

MATRIX OPERATION
Example
>> C = A^2 % Power
C =
30 36 42
66 81 96
102 126 150
>> C = A’ % Transpose
C =
1 4 7
2 5 8
3 6 9
Example
>> C = A*B % Multiplication
C =
21 30 39
54 78 102
87 126 165
>> C = A.*B % Element Multiplication
C =
2 8 18
32 50 72
7 16 27

MATRIX OPERATION
LEFT DIVISION () => C = AB = A-1B
RIGHT DIVISION (/) => C = A/B = AB-1
Example:
>> A = [1 2 3;4 5 6;7 8 9];
>> B = [2 4 6;8 10 12; 1 2 3];
>> C = AB % LEFT DIVISION
C =
-2.305556 -3.611111 -4.916667
-0.055556 -0.111111 -0.166667
2.194444 3.388889 4.583333

MATRIX OPERATION
>> C = A/B % RIGHT DIVISION
C =
4.0000e-01 1.5266e-16 2.0000e-01
4.8190e-16 5.0000e-01 3.8806e-16
-4.0000e-01 1.0000e+00 -2.0000e-01
SPECIFICALLY IN THE CASE OF MATRIX RULES, APPLICABLE
REQUIREMENTS FOR ANALYSIS OF MATRICES. WHERE THE REQUIREMENT
OF MATRIX MULTIPLICATION IS : THE NUMBER OF COLUMNS IN MATRICES
A = NUMBER OF LINES IN B MATRICES
THANK YOU AND GOOD LUCK
Source: Matematika Numerik dengan Implementasi Matlab, Julan Hernadi, Penerbit Andi (2012)

Basic of octave matlab programming language

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Basic of octave matlab programming language

Similar to Basic of octave matlab programming language (20)

Recently uploaded

Recently uploaded (20)

Basic of octave matlab programming language