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Statements
+ instructions to MATLAB
+ end statements by hitting Return or Enter
+ may also use a semicolon to end and suppress output
+ sometimes a comma (,) separates statements
+ MATLAB works top-down, left-right

(1)  empty
     + MATLAB automatically succeeds
     + shows up now and then

       <Return>
       ;

(2)  expression
     + MATLAB evaluates all operations
     + MATLAB reports result as output
     + result automatically stored in variable $ans$ if you do not 
       specify something else
     + operator precedence and associativity like Java
     + can suppress output with semicolon (;)

       1+1
       1/2;

(3)  declaration
     + in other languages, need to tell MATLAB about the data types
     + MATLAB is weakly typed!
     + everything is an array

(4)  assignment
     + want to reuse values
     + store results of expressions in variables
     + syntax: $var=value$
     + think in terms of "variable gets value"
       or pseudocode: variable<-value
     + to see a variable's value, enter variable at the prompt
     + cannot use a variable until it's assigned
     + variables assigned in the command window are GLOBAL
       (known until you reassign or clear)

       clear   % removes all assignments
       x       % causes an error because x is not assigned yet
       y+1     % same problem: y isn't assigned yet!
       x = 1   % x gets the value 1
       x+2     % MATLAB knows that x means 1, so x+1 produces 3
       clear x % remove the value in x
       x       % uh oh: cannot use x now because value is removed

(5)  function call
     + exectute a programmed procedure
     + either builtin or defined by user

       sqrt(4)
       rand

     + some functions generate values
     + replace the function's value in the expression

       x = 1 + sqrt(4)   % produces 3
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