-
Курсы
-
Другое
Курс повышения квалификации
Курс повышения квалификации
Курс профессиональной переподготовки
Курс повышения квалификации
1 слайд
MATLAB Basics
CS 111 Introduction to Computing in Engineering and Science
2 слайд
CS 111
2
MATLAB BASICS
Variables and Arrays
Array: A collection of data values organized into rows and columns, and known by a single name.
Row 1
Row 2
Row 3
Row 4
Col 1
Col 2
Col 3
Col 4
Col 5
arr(3,2)
3 слайд
CS 111
3
MATLAB BASICS
Arrays
The fundamental unit of data in MATLAB
Scalars are also treated as arrays by MATLAB (1 row and 1 column).
Row and column indices of an array start from 1.
Arrays can be classified as vectors and matrices.
4 слайд
CS 111
4
MATLAB BASICS
Vector: Array with one dimension
Matrix: Array with more than one dimension
Size of an array is specified by the number of rows and the number of columns, with the number of rows mentioned first (For example: n x m array).
Total number of elements in an array is the product of the number of rows and the number of columns.
5 слайд
CS 111
5
MATLAB BASICS
1 2
3 4
5 6
a=
3x2 matrix 6 elements
b=[1 2 3 4]
1x4 array 4 elements, row vector
c=
1
3
5
3x1 array 3 elements, column vector
a(2,1)=3b(3)=3c(2)=3
Row #
Column #
6 слайд
CS 111
6
MATLAB BASICS
Variables
A region of memory containing an array, which is known by a user-specified name.
Contents can be used or modified at any time.
Variable names must begin with a letter, followed by any combination of letters, numbers and the underscore (_) character. Only the first 31 characters are significant.
The MATLAB language is Case Sensitive. NAME, name and Name are all different variables.
Give meaningful (descriptive and easy-to-remember) names for the variables. Never define a variable with the same name as a MATLAB function or command.
7 слайд
CS 111
7
MATLAB BASICS
Common types of MATLAB variables
double: 64-bit double-precision floating-point numbers
They can hold real, imaginary or complex numbers in the range from ±10-308 to ±10308 with 15 or 16 decimal digits.
>> var = 1 + i ;
char: 16-bit values, each representing a single character
The char arrays are used to hold character strings.
>> comment = ‘This is a character string’ ;
The type of data assigned to a variable determines the type of variable that is created.
8 слайд
CS 111
8
Initializing Variables in Assignment Statements
An assignment statement has the general form
var = expression
Examples:
>> var = 40 * i;>> a2 = [0 1+8];
>> var2 = var / 5;>> b2 = [a2(2) 7 a];
>> array = [1 2 3 4];>> c2(2,3) = 5;
>> x = 1; y = 2; >> d2 = [1 2];
>> a = [3.4];>> d2(4) = 4;
>> b = [1.0 2.0 3.0 4.0];
>> c = [1.0; 2.0; 3.0];
>> d = [1, 2, 3; 4, 5, 6]; ‘;’ semicolon suppresses the
>> e = [1, 2, 3 automatic echoing of values but
4, 5, 6]; it slows down the execution.
MATLAB BASICS
9 слайд
CS 111
9
MATLAB BASICS
Initializing Variables in Assignment Statements
Arrays are constructed using brackets and semicolons. All of the elements of an array are listed in row order.
The values in each row are listed from left to right and they are separated by blank spaces or commas.
The rows are separated by semicolons or new lines.
The number of elements in every row of an array must be the same.
The expressions used to initialize arrays can include algebraic operations and all or portions of previously defined arrays.
10 слайд
CS 111
10
MATLAB BASICS
Initializing with Shortcut Expressions
first: increment: last
Colon operator: a shortcut notation used to initialize arrays with thousands of elements
>> x = 1 : 2 : 10;
>> angles = (0.01 : 0.01 : 1) * pi;
Transpose operator: (′) swaps the rows and columns of an array
>> f = [1:4]′;
>> g = 1:4;
>> h = [ g′ g′ ];
1 1
2 2
3
4 4
h=
11 слайд
CS 111
11
Initializing with Built-in Functions
zeros(n)>> a = zeros(2);
zeros(n,m)>> b = zeros(2, 3);
zeros(size(arr))>> c = [1, 2; 3, 4];
ones(n)>> d = zeros(size(c));
ones(n,m)
ones(size(arr))
eye(n)
eye(n,m)
length(arr)
size(arr)
MATLAB BASICS
12 слайд
CS 111
12
Initializing with Keyboard Input
The input function displays a prompt string in the Command Window and then waits for the user to respond.
my_val = input( ‘Enter an input value: ’ );
in1 = input( ‘Enter data: ’ );
in2 = input( ‘Enter data: ’ ,`s`);
MATLAB BASICS
13 слайд
CS 111
13
3
2
5
4
7
6
1
10
8
9
11
12
4
7
1
10
2
5
MATLAB BASICS
8
11
Multidimensional Arrays
A two dimensional array with m rows and n columns will occupy mxn successive locations in the computer’s memory. MATLAB always allocates array elements in column major order.
a= [1 2 3; 4 5 6; 7 8 9; 10 11 12];
a(5) = a(1,2) = 2
A 2x3x2 array of three dimensions
c(:, :, 1) = [1 2 3; 4 5 6 ];
c(:, :, 2) = [7 8 9; 10 11 12];
14 слайд
CS 111
14
Subarrays
It is possible to select and use subsets of MATLAB arrays.
arr1 = [1.1 -2.2 3.3 -4.4 5.5];
arr1(3) is 3.3
arr1([1 4]) is the array [1.1 -4.4]
arr1(1 : 2 : 5) is the array [1.1 3.3 5.5]
For two-dimensional arrays, a colon can be used in a subscript to select all of the values of that subscript.
arr2 = [1 2 3; -2 -3 -4; 3 4 5];
arr2(1, :)
arr2(:, 1:2:3)
MATLAB BASICS
15 слайд
CS 111
15
Subarrays
The end function: When used in an array subscript, it returns the highest value taken on by that subscript.
arr3 = [1 2 3 4 5 6 7 8];
arr3(5:end) is the array [5 6 7 8]
arr4 = [1 2 3 4; 5 6 7 8; 9 10 11 12];
arr4(2:end, 2:end)
Using subarrays on the left hand-side of an assignment statement:
arr4(1:2, [1 4]) = [20 21; 22 23];
(1,1) (1,4) (2,1) and (2,4) are updated.
arr4 = [20 21; 22 23]; all of the array is changed.
MATLAB BASICS
16 слайд
CS 111
16
Subarrays
Assigning a Scalar to a Subarray: A scalar value on the right-hand side of an assignment statement is copied into every element specified on the left-hand side.
>> arr4 = [1 2 3 4; 5 6 7 8; 9 10 11 12];
>> arr4(1:2, 1:2) = 1
arr4 =
1 1 3 4
1 1 7 8
9 10 11 12
MATLAB BASICS
17 слайд
CS 111
17
Special Values
MATLAB includes a number of predefined special values. These values can be used at any time without initializing them.
These predefined values are stored in ordinary variables. They can be overwritten or modified by a user.
If a new value is assigned to one of these variables, then that new value will replace the default one in all later calculations.
>> circ1 = 2 * pi * 10;
>> pi = 3;
>> circ2 = 2 * pi * 10;
Never change the values of predefined variables.
MATLAB BASICS
18 слайд
CS 111
18
Special Values
pi: value up to 15 significant digits
i, j: sqrt(-1)
Inf: infinity (such as division by 0)
NaN: Not-a-Number (division of zero by zero)
clock: current date and time in the form of a 6-element row vector containing the year, month, day, hour, minute, and second
date: current date as a string such as 16-Feb-2004
eps: epsilon is the smallest difference between two numbers
ans: stores the result of an expression
MATLAB BASICS
19 слайд
CS 111
19
Changing the data format
>> value = 12.345678901234567;
format short 12.3457
format long 12.34567890123457
format short e 1.2346e+001
format long e 1.234567890123457e+001
format short g 12.346
format long g 12.3456789012346
format rat 1000/81
MATLAB BASICS
20 слайд
CS 111
20
MATLAB BASICS
The disp( array ) function
>> disp( 'Hello' )
Hello
>> disp(5)
5
>> disp( [ 'Bilkent ' 'University' ] )
Bilkent University
>> name = 'Alper';
>> disp( [ 'Hello ' name ] )
Hello Alper
21 слайд
CS 111
21
MATLAB BASICS
The num2str() and int2str() functions
>> d = [ num2str(16) '-Feb-' num2str(2004) ];
>> disp(d)
16-Feb-2004
>> x = 23.11;
>> disp( [ 'answer = ' num2str(x) ] )
answer = 23.11
>> disp( [ 'answer = ' int2str(x) ] )
answer = 23
22 слайд
CS 111
22
MATLAB BASICS
The fprintf( format, data ) function
%dinteger
%ffloating point format
%eexponential format
%geither floating point or exponential format, whichever is shorter
\nnew line character
\ttab character
23 слайд
CS 111
23
MATLAB BASICS
>> fprintf( 'Result is %d', 3 )
Result is 3
>> fprintf( 'Area of a circle with radius %d is %f', 3, pi*3^2 )
Area of a circle with radius 3 is 28.274334
>> x = 5;
>> fprintf( 'x = %3d', x )
x = 5
>> x = pi;
>> fprintf( 'x = %0.2f', x )
x = 3.14
>> fprintf( 'x = %6.2f', x )
x = 3.14
>> fprintf( 'x = %d\ny = %d\n', 3, 13 )
x = 3
y = 13
24 слайд
CS 111
24
MATLAB BASICS
Data files
save filename var1 var2 …
>> save myfile.mat x y binary
>> save myfile.dat x –ascii ascii
load filename
>> load myfile.mat binary
>> load myfile.dat –ascii ascii
25 слайд
CS 111
25
MATLAB BASICS
variable_name = expression;
additiona + b a + b
subtractiona - b a - b
multiplicationa x b a * b
divisiona / b a / b
exponentab a ^ b
26 слайд
CS 111
26
MATLAB BASICS
Hierarchy of operations
x = 3 * 2 + 6 / 2
Processing order of operations is important
parentheses (starting from the innermost)
exponentials (from left to right)
multiplications and divisions (from left to right)
additions and subtractions (from left to right)
>> x = 3 * 2 + 6 / 2
x =
9
27 слайд
CS 111
27
MATLAB BASICS
Built-in MATLAB Functions
result = function_name( input );
abs, sign
log, log10, log2
exp
sqrt
sin, cos, tan
asin, acos, atan
max, min
round, floor, ceil, fix
mod, rem
help elfun help for elementary math functions
28 слайд
CS 111
28
MATLAB BASICS
Types of errors in MATLAB programs
Syntax errors
Check spelling and punctuation
Run-time errors
Check input data
Can remove “;” or add “disp” statements
Logical errors
Use shorter statements
Check typos
Check units
Ask your friends, assistants, instructor, …
29 слайд
CS 111
29
MATLAB BASICS
Summary
help command Online help
lookfor keyword Lists related commands
which Version and location info
clear Clears the workspace
clc Clears the command window
diary filename Sends output to file
diary on/off Turns diary on/off
who, whos Lists content of the workspace
more on/off Enables/disables paged output
Ctrl+c Aborts operation
… Continuation
% Comments
Рабочие листы
к вашим урокам
Скачать
Учебное пособие посвящено 3х-мерному компьютерному моделированию процессов тепломассопереноса при сжигании экибастузского угля в топках паровых котлов, описаны физическая и математическая модели поставленной задачи, а также методы решения уравнений, описывающих трехмерный процесс конвективного тепломассопереноса при сжигания твердого топлива в пылевидном с учетом радиационного переноса и многофазности среды. Актуальность моделирования процессов конвективного тепломассопереноса в реагирующих средах в камерах сгорания и растущее внимание к подобным исследованиям мировой общественности объясняется тем, что с ростом объема промышленного производства происходит резкое увеличение количества загрязняющих веществ, поступающих в биосферу. Перед многими странами, в том числе и Казахстаном, встала задача регулирования качества окружающей среды в связи с ущербом, наносимым природе производственной деятельностью человека.
7 365 682 материала в базе
Настоящий материал опубликован пользователем Аскарова Алия Сандыбаевна. Инфоурок является информационным посредником и предоставляет пользователям возможность размещать на сайте методические материалы. Всю ответственность за опубликованные материалы, содержащиеся в них сведения, а также за соблюдение авторских прав несут пользователи, загрузившие материал на сайт
Если Вы считаете, что материал нарушает авторские права либо по каким-то другим причинам должен быть удален с сайта, Вы можете оставить жалобу на материал.
Удалить материал
Вам будут доступны для скачивания все 356 588 материалов из нашего маркетплейса.
Мини-курс
3 ч.
Оставьте свой комментарий
Авторизуйтесь, чтобы задавать вопросы.