3.1 Variables in m-file environments

Variables

A variable is a named storage location that can be set to a particular value which can be used in subsequent computations. For example, we store a value of 5 in the variable a with the statement a=5 . This value remains in a until we store a different value (for example, using the command a=100 ) or we clear a using the command clear a . Once a variable is set to a particular value, we can get this value by using the variable name in an expression (e.g. a/2 ).

Variable names must begin with an upper- or lower-case letter. They may contain letters, digits, and underscores; they may not contain spaces or punctuation characters. Variable names are case sensitive, so A and a are different variables.

There are several predefined variables. The most commonly used include

• ans - the default variable in which computation results are stored.
• pi -.
• i or j - $\sqrt{-1}$ .

Variables can contain several types of numerical values. These types include the following:

• Scalar - a scalar is a single value (i.e. a number). c and d in are scalar variables.
• Vector - a vector is an ordered series of numbers.
• Matrices - a matrix is a rectangular array of numbers. The ability to do computations on vectors and matrices gives MATLAB its name (MATrix LABoratory).
• strings - variables may also contain strings of characters.