1.4 Variables

Variables are a place to store values and results. For example, try this:

x = 2
x

What happened? When you typed x=2, MATLAB assigned the value of 2 to the variable x. When you typed x, MATLAB returned the value of x. Try typing y instead. MATLAB complains because the variable y has not yet been assigned a value and is therefore undefined. It is important (even if you don't understand yet why) NOT to read x=2 as ``x equals two.'' That is not what it means! To MATLAB, the statement x=2 means ``assign the variable x the value of 2.'' The = symbol is an assignment operator. (The ``equality'' operator is ==. Incidentally, this is generally true for all programming languages, not just MATLAB.) The = assignment operator works not only for values but also for expressions. Try,

y = 2+2
z = y*3
a = z+y
b = a+z-y

Make sure you understand why MATLAB gives the answers it does. Notice that the quantity being assigned to a variable can even be another variable itself or an expression including other variables.