Summary: This module provides a brief introduction to the use of variables in m-file environments.
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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).
Suppose we wish to compute the circumference of a circle of diameter 5 units using the formula
d to a value of 5:
>> d = 5
d =
5.000
c:
>> c = pi*d
c =
15.708
d
(which is known because we earlier set it to 5) and the value of pi (which is a pre defined variable) is computed and the value of the product is stored in the variable c.
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.
Which of the following are valid variable names?
a B ecky_ecky_ecky_ecky_ptang_zoo_boing ecky ecky ecky ecky ptang zoo boing 2nd John-BigbooteThere are several predefined variables. The most commonly used include
ans - the default variable in which computation results are stored. pi - π. i or j -
clear command.
Variables can contain several types of numerical values. These types include the following:
c and d in Example 1 are scalar variables.