ENGR 111: MATLAB Test 2 Ch 2-5

Each MATLAB variable has a specific ____, also referred to as a data type, to indicate the type of data stored in the variable, such as the type of number or letter

class

Clears the command window. Does not affect the workspace, meaning variables are unchanged.

clc

Clears all variables from the workspace, so all variable values are lost.

clear

is text added to provide explanation of a program for humans to read and does not affect how the program runs. The "%" symbol supports a single-line _________. The interpreter ignores all text to the right of "%" on a line, so the programmer can write any text there.

comment

log10(x)

common logarithm

While not a MATLAB command, this keystroke sequence interrupts an endless MATLAB calculation that a programmer may have entered accidentally. Afterwards, the programmer can enter a new command.

ctrl-c

is a numerical value consisting of a real part and an imaginary part. The variables i and j are predefined values for representing the imaginary component of a ________. (can be used in loops)

Complex Number Ex: numA = 5 + 4j

Finite precision of numerical calculations

Rounding error

Imaginary unit equal to sqrt(-1), same as i

j

Identifiers must start with a _____

letter

log(x)

natural logarithm (logarithm with base e)

stores a number. A ________can either be an integer number or a real number.

numeric variable

is a positive or negative number that may have a fractional part

real number (9.62)

smallest floating point number

realmin

are described in the following table, where a scalar is a single number, and a scalar variable refers to a variable that stores one number.

scalar arithmetic operators

is a sequence of statements stored in a text file. MATLAB requires that the name of a ______ file must end in .m, in order to be executable by the MATLAB interpreter. Statements within a _______ are executed line by line from top to bottom as if the statements were directly entered on the command line. (don't end in semicolon)

script

represents both positive and negative integer values

signed integer

tell the MATLAB interpreter to store the character as a unique 8-bit ASCII number.

single quotes

represents only non-negative integers

unsigned integer

(such as age = 20; or nextAge = age;) upon being executed, writes the current value of the item on the ='s right side into the variable on the ='s left side.

Assignment statement

print a single quotation mark. Note that a single quotation mark alone would instead indicate the end of the format string.

" (double quotation marks)

print one percent character. Note that a single % character would instead indicate the start of a formatting operator like %f.

%%

Scientific notation with capital E, as in 3.141593E+00

%E

Either %f or %E, whichever is shorter

%G

is for character

%c

d is for decimal integer. The use of 'd' is due to historical reasons, and is slightly misleading because a decimal number could have a fractional part. In MATLAB, ____ means decimal integer which does not have a fraction.

%d

Scientific notation with lowercase e, as in 3.141593e+00

%e

Fixed-point notation

%f

Either %f or %e, whatever is shorter

%g

i is for integer. This operator is identical to %d when formatting output.

%i

is for string

%s ex: exitChar = 'q'; exitStr = 'quit'; fprintf('Enter %c or %s to exit.', exitChar, exitStr); Command window prints: Enter q or quit to exit.

Specifies left-justified display. Without this item, the default is right-justified.

-

fprintf('10 inch: %5.2f, prc/sqin: %.4f \n', cost10, prcPSqIn10); fprintf('12 inch: %5.2f, prc/sqin: %.4f \n', cost12, prcPSqIn12); fprintf('16 inch: %5.2f, prc/sqin: %.4f \n', cost16, prcPSqIn16);

10 inch: 9.95, prc/sqin: 0.1267 12 inch: 11.95, prc/sqin: 0.1057 16 inch: 14.95, prc/sqin: 0.0744

5e3 =

5000

Addition subtraction, multiplication(*) and division(/) and exponentiation (^)

Arithmetic operator

avg = 14.777; fprintf('The average is %f kilograms.\n', avg) fprintf('The average is %e kilograms.\n', avg) fprintf('The average is %E kilograms.\n', avg)

Command Window reads: The average is 14.777000 kilograms. The average is 1.477700e+01 kilograms. The average is 1.477700E+01 kilograms.

Limited accuracy of the measurement apparatus

Experimental Error

A reference to the function's name, as on the command line above, is known as a ___________

Function call

are comments that appear at the beginning of a function after the function name and arguments but before the first statement and automatically prints the help comments for a given function.

Help comments

Use clear ___ (name of variable)___ to remove previous variable

NOTE

A common special character is ______, which prints a new line. The \ and n together are considered one special character, known as a ______ control sequence

Newline ('\n') ex: amt = 99.42; fprintf('The final amount\nwill be:', amt); Prints on command window: The final amount will be: 99.42

Number that specifies the number of digits to the right of the decimal point

Precision

% A game inspired by "Mad Libs" where user enters nouns, % verbs, etc., and then a story using those words is output. fprintf('Provide input without any spaces.\n'); relative = input('Enter a type of relative: ', 's'); food = input('Enter a type of food: ', 's'); adjective = input('Enter an adjective: ', 's'); period = input('Enter a number: ', 's'); % Tell the story fprintf('\nMy %s says eating %s\n',relative, food); fprintf('will make me more %s \n',adjective); fprintf('so now I eat it every %s days\n',period);

Provide input without any spaces. Enter a type of relative: brother Enter a type of food: oranges Enter an adjective: good Enter a number: 10 My brother says eating oranges will make me more good so now I eat it every 10 days

The interpreter will not prit the output of a statement ending with this

Semicolon (;)

refers to the parts of a program that can access that variable's value. Recall that a variable defined in the workspace can be accessed by any statement executed at the command line, or by any script run from the command line.

The Scope (of a variable)

is defined as how close the stored number is to the desired value.

The accuracy of a floating-point number

print one backslash character. Note that a single backslash character would instead indicate the start of a special character sequence like \n.

\\

Prints a new line.

\n

Prints a tab.

\t

A floating-point number can be formatted in various ways by following the % character with a different ______________ f, e, g, E, or G, as follows:

conversion character

is a list of statements that a programmer creates and gives a specific name such as LightningDistance, with the function being stored in a file LightningDistance.m. The programmer can then execute those statements elsewhere simply by referring to the function's name

custom function

function is a less used function than fprintf that outputs unformatted variables to the command window without outputting the variable's name.

disp ex: radius = 3; circumference = 2 * pi * radius; disp(circumference); Command Window reads: 18.8496

(short for epsilon) is a built-in MATLAB command. If a double-precision computation returns the answer num, the result is only absolutely accurate to within eps(num), and relatively accurate to within eps(num)/num.

eps

Exits the MATLAB session.

exit

is a combination of items like variables, constants, and operators, that results in a value.

expression

Number that specifies the minimum number of digits that will be displayed. If the actual number of digits is less, spaces are automatically inserted to reach the minimum.

fieldWidth

The act of providing input values during a function call is known as ___________ values to the function, with those values known as ____________. A variable created inside a function, such as speedOfSound above, is known as a __________ and does not exist outside the function.

passing arguments local variable

fprintf('A circle''s diameter is 32%% of its circumference.\n');

prints on command window: A circle's diameter is 32% of its circumference.

Special two-character sequences, each known as a_________, can be used to print special items in a format string.

special character

defined in the same m-file have a separate function workspace, which means that any variable defined in the workspace of a subfunction is local and only available within that subfunction.

subfunctions

finds the absolute accuracy of the valued stored within the variable aNum. The relative accuracy is given by eps(aNum)/aNum and this value will never exceed eps(1)/1 or eps(1).

The command eps(aNum)

The "=" is known as the _____________

assignment operator

Prints all variables in the current workspace.

who

Example of rounding error:

>> aVal = 4 / 3 aVal = 1.3333 >> bVal = aVal - 1 bVal = 0.3333 >> cVal = bVal + bVal + bVal cVal = 1.0000 >> error = 1 - cVal error = 2.2204e-016

operator prints a floating-point number using fixed-point notation.

%f

A string rather than a number can be obtained from the user by the programmer passing a second argument ___ to the input function: treats input as a string (word) even if its a number

's' ex: myStringVar = input ('Text prompting user to enter a string: ', 's');

precedence rules for arithmetic operators:

( ) Items within parentheses are evaluated first ^ Power is evaluated next. Thus 2^3*3 evaluates as (2^3)*3 or 8*3 which is 24. * / Next to be evaluated are * and / having equal precedence. + - Finally come + and - with equal precedence. Thus, 3+2*A is evaluated as 3+(2*A) . left-to-right If more than one operator of equal precedence could be evaluated, evaluation occurs left to right. Thus, A*2/3;" evaluates as (A*2)/3

an epression that indicates that an equation continues on the next line

. . . (tree periods spaced) ex: >> x1 = (1/2)^1+(1/2)^2+(1/2)^3+... (1/2)^4+(1/2)^5+(1/2)^6+... (1/2)^7+(1/2)^8+(1/2)^9;

Exaple of up-arrow key:

>> height = 1; bounce = 0; distance = 0; >> height = 0.75 * height; bounce = bounce + 1, distance = distance + 2 * height bounce = 1 distance = 1.5000 (press up-arrow key) >> height = 0.75 * height; bounce = bounce + 1, distance = distance + 2 * height bounce = 2 distance = 2.6250 (press up arrow key) >> height = 0.75 * height; bounce = bounce + 1, distance = distance + 2 * height bounce = 3 distance = 3.4688 (etc....)

Initially capitalizing each word is known as ________ because the capital letters appear like the humps on a camel.

Camel Case

which has the class char, stores a single character like the letter 'm' or the symbol '%'. Values of type char are denoted by single quotes (e.g., myChar = 's').

Character variable

Multiple MATLAB statements can appear on the same line by separating those statements with a ______ or __________. A statement followed by a _______ will have its result printed, while a statement followed by a ________ will not have its result printed.

Comma or Semicolon Comma Semicolon

is to overwrite the value in a variable before that variable's value was used. ex: >> firstBid = 85 firstBid = 85 >> secondBid = 119 secondBid = 119 >> firstBid = secondBid firstBid = 119 >> secondBid = firstBid secondBid = 119

Command error

provides the basic method in which a programmer types statements to be executed by the MATLAB interpreter and presents users with interactive environment.

Command window

Commands that alter how output appears in the command window

Format commands

Numbers are displayed using a fixed-point representation , wherein each number is displayed with a fixed number of digits after the decimal point, the default being 4 digits after the decimal point. The Long command sets the display to show 15 digits after the decimal point and short commands returns to display 4 digits.

Format long/short

AnswerLookedFor = variableName(var1, var2, var3)

Function (at beginning of code)

which provides information on how to use internal functions, can be obtained from the command line, as summarized in the following table.

Function documentation

are comments that appear at the beginning of a script file before the first statement. The help command prints the help comments for a given script.

Help comment EX: >> help ConeVol Computes volume of a cone. Creates variables radius and height. Result is assigned to variable volume and displayed.

Usually does not matter Ex: Hoursperweek=4; Hoursperweek = 4 ;

Horizontal space (white space)

A variables name. A valid ______ consists of a sequence of letters (a-z, A-Z), digits (0-9), or underscores (_), and must start with a letter. Other symbols are not allowed. Upper and lower case letters differ, meaning MATLAB is case sensitive, so variables named "balance", "BALANCE" and "Balance" represent three different variables.

Identifier

infinity

Inf

is a variable that has a logical data type (class).

Logical variable

are special variables with predefined numerical values (e.g., pi) built into MATLAB.

Mathematical Constants

Not-a-number

NaN

is the difference between the calculated approximation of a number and the exact mathematical value.

Rounding errow

is an indication of the actual numbers that can be represented, usually written from smallest to largest.

The range (of a number class)

Discarding the least significant digits or a numerical result

Truncation error

A useful feature of the MATLAB command line is that a command (or sequence of commands) from a previously-entered line can be retrieved by pressing the _________ key

Up-arrow

is a named place for a programmer to store data in memory. A programmer defines a new ______ by writing a statement like age = 20;

Variable

Displays current data being used by the computer

Workspace

which is the difference between the calculated value and the actual value.

absolute error eps(number)

Assign variable allowBoat with string: OK'ed

allowBoat = 'OK''ed' (two single quotes)

is 8 bits

byte

Records into a file almost everything that appears in the command window. The file's name is chosen by the programmer, such as "mysession.txt". "diary off" ends the recording.

diary

Detailed information on the function known as functionname

doc functionname

a way that a programmer can check whether a name already exist in a current workspace:

exist ___(name of variable)_____ If: result is ans = 1 then it means that MATLAB interpreter already recognizes that name and a different name should be chosen.

which is the difference between a measured value and the actual value of the quantity being measured.

experimental error

The command window by default prints output text using vertical double spacing. The ________ command changes to single spacing. ________ reverts to double spacing. Many subsequent examples will be shown using compact output.

format compact format loose

Above, the fprintf function call has a single argument consisting of a string and can contain literal text as above, as well as formatting operators and special characters as described below.

format string

indicate that a value should be printed at that place in the string, such as the %f operator below.

formatting operators ex: amt = 99.42; fprintf('The final amount will be %f units.', amt); This will appear on command window as: The final amount will be ______ units

function prints formatted output from a program.

fprintf ex: fprintf ('The final amount will be: '); (prints on the command window as: The final amount will be: ____)

List of the elementary mathematical functions

help elfun

Summary of how to use the function known as functionname

help functionname

List of the advanced specialized mathematical functions

help specfun

Imaginary unit equal to sqrt(-1)

i

Numerical input from a user can be obtained with the ______ function and stored into a variable

input ex: celsius = input('Enter a temperature in Celsius: '); fahrenheit = ((9*celsius) / 5) + 32

is a positive or negative number that does not have a fractional part.

integer number (9)

is a value that is either true (indicated by a non-zero number, typically 1) or false (indicated by the number 0).

logical data type

clear x

only clears the stated value of x

occurs when the result of a expression exceeds the maximum value that can be stored within a variable.

overflow

may be used in expressions to dictate a specific order of operations

parentheses

The ratio of circle's circumference to its diameter, which is approximated as 3.14159265...

pi

Largest floating point number

realmax

which is the difference between the calculated value and the actual value divided by the actual value.

relative error

is any sequence of characters, including special characters like "$" or numbers like "9". In MATLAB, a ______ is not a separate data type (class), but rather a sequence (i.e., array) of characters.

string

A _____ variable is defined by enclosing the characters in single quotes.

string Ex: >> name = 'Julia!' name = Julia! >> happyMessage = 'Isn''t today a great day?' happyMessage = Isn't today a great day?

of a number represented in floating point, which is given by eps(aNum), decreases with the magnitude of aNum. Stated differently, the absolute error gets larger with the magnitude of aNum. It is the relative accuracy that will be bounded by eps(1).

the absolute accuracy

that occurs when the least significant digits to the right of the decimal point are truncated (i.e., discarded).

truncation error

Prints all variables in the current workspace as well as some extra information about their size, bytes, class, etc.

whos