Intro Chapter 1 Demo Help Lookfor Doc Quit exit Variable variablename = expression = assignment operator, initializing Incrementing Identifier names

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1 Intro Ways to execute a code -GUI or IDE (command line) Ssh - secure shell (gets machine into the main shell) 259 Avery office () means its a function Mod (clock arithmetic) No semicolon gives you an answer ~ means not 0-false 1-true Chapter 1 Demo will bring up examples Help will explain any function Lookfor searches through help for a specific word or phrase Doc will bring up a documentation page in the help browser Quit or exit to quit Variable to store a value in a program. They re shown in the workspace window on the right and you can use an assignment statement variablename = expression = is an assignment operator, not an equal sign ; suppresses the output (if there s no semicolon it will say the answer right then) The up arrow goes back to the previously typed command if you need to make a change. You can also change a variable with a new assignment operator Putting the initial value in a variable is called initializing the variable Incrementing is adding to a variable (ex mynum = mynum + 1) Identifier names must begin with a letter but can include numbers and _, there s a difference between capital and lowercase letters, there are some reserved words that cannot or should not be used, and should make sense. If you don t declare a name it will be ans Who shows names of variables that have been defined in the command window Whos shows variables and their values Clear clears all variables. You can clear variablename or a list of names also Every variable has a type and a class is a combination of a type and operations that can be performed on values of that type (they re kinda interchangeable tho) Two types of ways to store numbers- single or double (larger numbers). Integer types ( int# ) represent the number of bits used to store the values. Unsigned int types ( uint# ) can only be positive. Char stores single characters or strings. Logical stores true/false values Format long shows 15 decimal points instead of 4 in format short Unary operators operate on a single value vs operand and binary which operate on 2 values or operands If you start to type a function then hit tab a list of functions that start like that will pop up Rand generates random numbers in the open interval (0,1) (endpoints not included) Rng ( shuffle ) (intseed) ( default )

2 To generate a random number on any interval pg 17. To make the interval 0 to x type rand*x Randi(imax) returns a random integer from 1 to imax(maximum integer) % comment A character (basically anything on the keyboard) must be in or it will be read as a variable name String sequences of characters in single quotes Relational expressions / Boolean expressions / logical expressions expressions that are conceptually true or false Relational operators: <, >, <=, >=, ==(equal), ~=(inequality) 1 is true 0 is false (these are logical values) Logical operators or, && and, ~ not(will give the opposite answer), xor (only one if true) Short circuit operator if they can tell the answer from the first term they won't go any further Operator precedence rules pg 22 Range intmin/max( int# ) to find it ASCII American Standard Code for Information Interchange (each character is assigned to an integer 0-127) Numequiv=double( a ) to find a letter s numerical equivalent Char(#) converts numbers to characters Double( xyz ) will show you the value of all characters in the string Rem and mod return remainder Chapter 2 Vectors(x, 1) and matrices(x, y) used to store values(called elements) of the same type r by c. Row matrix=1 by n. Column matrix=n by 1. Scalar matrix=1 by 1 matrix=array=vector v=[values separated by spaces or commas] Colon operator 2:6 gives you or 1:2:9 (first:step value:last) gives you Linspace (x,y,n) creates a linearly spaced vector with n values from x to y inclusive. If n is not included the default is 100 Logspace(x,y,n) logarithmically spaced vector from 10^x to 10^y with n values(default n=50) Concatenating is putting 2 vectors together to make a new one vecname(#) shows the value in that index/subscript (starts at 1) Column vector = [1; 2; 3] Transpose to change a row vector to column 123 Linear indexing or subscripted indexing (r, c) 456 Reshape (change dimensions 3x4 to 2x6), fliplr, flipud, flip, rot90 (counterclockwise 90) Repmat(mat, m, n) creates a larger mxn matrix with copies of mat layerone/two=(reshape, c, r) Min max sum prod(vec) Cumulative sum/prod/min/max pg 53

3 Use.* or./ for array multiplication/division For arrays use and & not and && Matrix multiplication columns in A must be equal to rows in B If A is mxn and B is nxp then C is mxp Order of precedence Parenthesis ( ) Transpose and power ^ Unary: negation -- not ~ Multiplication/division * / \ Addition/subtraction + - Relational < > <= >= == ~= & && Assignment = fprintf( text %f, var) \n new line Function name (); end Chapter 3 Top-down design breaking down a problem into separate steps and refining them all to manageable tasks Prompting telling the user what to enter Get input, calculate result, display result Block comment first comment at beginning of script that says what it does If you want a character/string, add s to the end of an input Disp displays a result, very basic Fprintf %d is a place holder-specifies where the value at the end of the string should go %d (decimal) integer %f float(real number) %c character(1) %s string of characters \n new line, put at end of fprintf Field width specifies how many characters total are to be used in printing (%.3f = number with 3 decimal points) Clf clears figure window Figure creates a new, empty figure window. Can also add (n) to create and maintain multiple figure windows and refer to them each individually

4 Hold freezes the current graph Legend displays strings passed to it in a legend box in the figure window Grid displays grid lines on a graph Function outputargument = name of function (inputargument) %comment describing function Body statements end Chapter 6 -functions can calculate and return one or more values or accomplish a task such as printing something without returning any values -the function header (first line) has function, the name of the output argument if the function returns a value, =, the name of the function (same as file name), the input argument in parentheses (if any, separated by commas) -then put a comment to be printed if you type help and the body (which should put values in the output arguments), then end Modular program the solution is broken down into modules and each is implemented as a function. They are all called in the main program Scope of a variable the workspace in which it is valid. The workspace created in the command window is called the base workspace -variables can be used in both the command window and a script but not the command window and a function(unless used as input or output arguments) -it is better coding to use all functions rather than a mix of functions being called in a script Persistent variables normally, all local variables are cleared when a function is done running. Type persistent variablename to declare it as persistent. Type clear functions to clear the variable Debugging process of finding errors and correcting them 3 types of errors-syntax(using the language(missing punctuation of misspelling)), runtime(found when the function is executing, such as divide by 0 or calling an element in an array that doesn t exist), logical(mistake in reasoning, doesn t result in an error message Echo functionname on/off to display every statement as it is executed and its results Help debug Chapter 4 Selection/branching statements-choose between or among statements -logical false can only equal 0 but logical true can be any number 1 or greater -instead of fprintf, you can use error() -switch statements can be used instead of if else/elseif statements -used when an expression is tested to see whether it is equal to one of several possible

5 values -form: Switch switch_expression (this is compared to all the case expressions) (must be scalar or a string) Case caseexp1 (if something matches this expressions, this action will execute) Action1 Case caseexp2 Action 2 Otherwise (there doesnt have to be an otherwise) Action n End Ex-switch quizgrade Case {10, 9} grade=a Case 8 grade=b, etc isletter( )- returns logical true or false depending on if the input is a letter of the alphabet isempty()- returns true if a variable or string is empty, false if it has a value, error if the variable doesn t exist iskeyword( )- determines whether or not something is the name of a keyword in MATLAB Chapter 5 for=counted loop while=conditional loop, used when you don t know how many times to repeat it -statements that are repeated are the action of the loop -iterator value/loop variable-how many times to go through a for loop Subplot(r,c,n)- creates a matrix of plots in the current figure window, r and c are dimensions of the matrix and n is the number of plots in the matrix Don t forget to preallocate matrices -the action of while loops is repeated as long as the condition is true For i= 1:rows For j= 1:col %something with mat(i, j) end End Cumsum cumprod- return a vector of the running sums or products checkcode() to check for efficiency and detect potential problems -when using loops, store all the data in an array if you ll need it later Chapter 7 String- consists of any numbers or characters and is enclosed in, a vector of characters

6 Substring- any part of a string String concatenation- joining strings together [name1 name2] Sprintf- creates a string. Useful to create strong customized by user. Doesn t print anything though. It can be displayed using input deblank() removes blank spaces upper/lower() makes a string all upper or lowercase Strcmp- compares string character by character Strrep(string, oldsubstring, newsubstring) - find all occurrences of a substring within a string and replaces them with a new substring Int2str str2int num2str str2num str2double Chapter 8 Data structures- variables that store more than one value. An array is a data structure Cell array- data structure that stores values of different types, often used to store strings. Use {} Structures- data structures that group together values that are logically related but not the same thing and not necessarily the same type. Are separated into fields Structs- the way to store records package=struct( item_no, 123, cost, 19.99, price, 39.95) can also use a dot operator like name.value -cell arrays can be useful to store strings of different lengths and not adding trailing blanks strjoin/strsplit- can join all strings from a cell array into one string separated by one space each/can split elements into cell arrays Categorical arrays- stores a finite,countable number of different possible values Table()- creates a table with information listed in cell arrays sortrows()- to sort strings in a matrix alphabetically Chapter 10 varagin/nargin/varagout- input/output arguments that can vary in number Anonymous functions- a simple one line function that does not need to be stored in a separate file functionhandle (arguments) function body How you refer to it things being passed to function any matlab expression The () must still be in the handle even if there are no arguments (ex using fprintf) Notes from Practice Midterms -if you multiply a double array by a single or logical, it will return multiple of the leftmost value of the other Feof- tests for end of file Fgetl- gets next line GUI- graphical user interface-how the user interacts with the program Event driven programming- program where the flow is affected by user interaction

7 Book-ewohlers mid15/16 jdong notes-kotto get/set- functions used to directly retrieve and modify properties

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