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Chapter 1 Slide 1ME280 - Structured Programming
MATLAB Windows
Default View
Command Window main window to enter commands and run programs
Current Folder Window shows MATLAB m-files in the current folder
Workspace Window provides information about currently used variables
Command History Window log of commands entered in the command window
Chapter 1 Slide 2ME280 - Structured Programming
MATLAB Windows
Additional Windows
Figure Window displays graphs from graphics commands automatically upon execution of the graphics command
Editor Window provides capability for writing and editing programs and is opened under the File New Script menu or button
Help Window provides help information interactively and is accessed via the Help menu or F1
Chapter 1 Slide 3ME280 - Structured Programming
MATLAB Windows
Configuring MATLAB
Close an individual window within MATLAB by clicking the in the upper right corner of the window
Desktop Layout menu provides options for opening and closing various MATLAB windows or combinations of MATLAB windows
Undock a window by clicking and then in the upper right corner of the window
Redock by toggling in the upper right corner of the window
Chapter 1 Slide 4ME280 - Structured Programming
Command Window
Entering commands once a command is entered it cannot be modified and reexecuted
>> denotes the command line prompt
Edit commands before they are executed by using backspace, left-arrow, right-arrow and delete keys
Select and edit previous commands entered using the or
Smart recall retrieves previously entered commands based on the first few characters of the command and the up-arrow key
Tab completion allows automatic completion of a previously defined name based on the first few letters of the name
Semicolon (;) prevents the value of a command from being written
Commas (,) or semicolons (;) allow several commands on the same line
Ellipse () may be used to continue a long command onto another line
% symbol denotes a comment line that is not executed (documenting)
Chapter 1 Slide 5ME280 - Structured Programming
Scalar Arithmetic Operators
Mathematical Operators
Addition (3 + 5 or a + b)
Subtraction (7 3 or a b)
Multiplication (6 * 4 or a * b)
Division (2 / 3 = 3 \ 2 or N / D = D \ N)
Exponential ( 5 ^ 3 or a ^ b)
Order of Precedence
Parentheses starting from the innermost
Exponentiation
Multiplication and division
Addition and subtraction
Chapter 1 Slide 6ME280 - Structured Programming
Answer Display
Format Command - changes the display format of numbers
Style Result Example
short (default)Short fixed decimal format, with 4 digits after the decimal point. If you are displaying a matrix with a
wide range of values, consider using shortG 3.1416
longLong fixed decimal format, with 15 digits after the decimal point for double values, and 7 digits after
the decimal point for single values. 3.141592653589793
shortE
Short scientific notation, with 4 digits after the decimal point. Integer-valued floating-point numbers
with a maximum of 9 digits do not display in scientific notation. 3.1416e+00
longE
Long scientific notation, with 15 digits after the decimal point for double values, and 7 digits after
the decimal point for single values. Integer-valued floating-point numbers with a maximum of 9
digits do not display in scientific notation. 3.141592653589793e+00
shortG The more compact of short fixed decimal or scientific notation, with 5 digits. 3.1416
longGThe more compact of long fixed decimal or scientific notation, with 15 digits for double values, and
7 digits for single values. 3.14159265358979
shortEngShort engineering notation, with 4 digits after the decimal point, and an exponent that is a multiple
of 3. 3.1416e+000
longEngLong engineering notation, with 15 significant digits, and an exponent that is a multiple of 3.
3.14159265358979e+000
bankCurrency format, with 2 digits after the decimal point. 3.14
Chapter 1 Slide 7ME280 - Structured Programming
Answer Display
Format Command - changes the display format of line spacing
Style Result Example
compact
Suppresses excess line feeds to show more output in a single screen. Contrast with loose. theta = pi/2
theta =
1.5708
loose
Adds linefeeds to make output more readable. Contrast with compact. theta = pi/2
theta =
1.5708
Chapter 1 Slide 8ME280 - Structured Programming
Functions
Mathematical Functions
Absolute value (abs)
Sine (sin or sind), cosine (cos or cosd), tangent (tan or tand), arcsine (asin), arccosine (acos), arctangent (atan or atan2)
Round (round), ceiling (ceil), floor (floor)
Square root (sqrt)
Natural logarithm (log), logarithm base 10 (log10)
Many others use shift+F1 to browse available functions
General Functions
Clock provides a vector as [year month day hour minute second]
Date provides the current date as dd-mm-yyyy
Calendar provides a calendar for the current month or specified month and year
Many others
Chapter 1 Slide 9ME280 - Structured Programming
Scalar Number
Constants
pi ()
eps represents the smallest difference between two numbers ( 2.2204e-16)
i or j represents the imaginary number
Indefinite numbers
Infinity is a valid input and is designated by Inf
Division by zero gives a warning and returns Inf
Not-a-Number is an undefined value designated by NaN
Returned by calculations such as 0 / 0
Chapter 1 Slide 10ME280 - Structured Programming
Variables
Variables - fundamental to programming and are actually pointers to allocated memory space
for storage
Name starts with a letter character
Name may only have letters, underscore, and the digits 0-9
Should not conflict with exiting variables or functions built into MATLAB
It is possible to reassign Inf for example but it may become confusing
Often i or j are reassigned as loop variables when a program does not deal with complex numbers
MATLAB is case sensitive
Assign using the equals operator (a = 2, a = 2 * b, a = sin(pi))
Reassignment in terms of themselves (a = 3 * a - 7, NOT the same as 2a = 7)
Cannot be defined as a MATLAB keyword such as (for, if, else, break, etc.)
If defined as an existing MATLAB function, function cannot be used
ans variable of the last expression calculated not assigned to a variable
Chapter 1 Slide 11ME280 - Structured Programming
Useful Management Commands
Commands
who - provides a list of variable names in the current workspace
whos provides a list of variables currently in memory and information about their size and type
clear - deletes all the variables stored in memory and shown in the current workspace
clear VarName1 VarName2 etc. removes only the listed variables from memory
clc clears the command window including those of previous sessions
ans - returns the value of the last expression calculated that was not assigned to a variable
Should avoid relying on the ans variable
Chapter 1 Slide 12ME280 - Structured Programming
Script Files Introduction
Command Window
Executes a single command at a time
Cannot be saved and executed again
Not interactive
Changing the value of a variable in equations previously entered requires reentering all equations affected by the variable change
Script Files
File with a list of commands that are executed sequentially in the same manner as the command window
Can be edited and saved as an M-file (*.m) for later use
Any text editor such as Notepad may be used to write a script file
MATLABs Editor Window assist with code development by issuing warnings, providing autocomplete, and color coded text
Chapter 1 Slide 13ME280 - Structured Programming
Script Files Use
Creating
Use the MATLAB Editor Window since MATLAB is available to all students and the Editor Window permits the execution of the script file from within and debugging tools
From MATLAB open the editor window by one of the following:
File New Script menu New script File button Ctrl + N
Saving
File name requirements are the same as variable names
From Editor Window save your M-file by one of the following:
File Save as menu
Save File button
Ctrl + S
Chapter 1 Slide 14ME280 - Structured Programming
Script Files Use
Opening
From MATLAB Desktop or Editor Window
File Open menu
Open File button
Ctrl + O
From the Current Folder Window
Select the appropriate directory for the M-file
Double click the file Right click the file and select open Select the file and use Ctrl+D
Chapter 1 Slide 15ME280 - Structured Programming
Script Files Use
Running
From the MATLAB Editor Window do one of the following:
Debug Run ScriptFileName menu
Run button
F5
From MATLAB Current Folder Window do one of the following:
Right click the appropriate M-file and select Run
Select the desired M-file and press F9
From MATLAB Command Window
Change to the desired M-files directory if necessary
cd C:\FilePath (useful for programs executing subprograms in different directories) Browse in MATLAB Desktop
Type the name of the M-file to run
Chapter 1 Slide 16ME280 - Structured Programming
Examples
Problem 1
Problem 2
Define the variables a and b as: a=14, b= 21 then evaluate:
Problem 3
Define the variables x as x =12 degrees and verify the identity is correct:
3 5
3
4 14 30ln50
5 30
456!
ln 90
e
10
sin coslog
ba ba a e a
a b b
31
sin 3sin sin 34
x x x
Chapter 1 Slide 17ME280 - Structured Programming
Examples
Problem 4
The prices of an oak tree and a pine tree are $54.95 and $39.95, respectively. Change the display format to bank, and calculate the following:
(a) the total cost of 16 oak trees and 20 pine trees.
(b) the same as part (a), and add 6.25% sale tax.
(c) the same as part (b) and round the total cost to the nearest dollar.