When you do long calculations, it is often convenient to give names
to your intermediate results. Just as in standard mathematics, or in other computer languages, you can do this by introducing named variables
This sets the value of the variable x
to be 5
now replaces it with the value 5
This assigns a new value to x
is set to be the numerical value of
to 40-digit accuracy.
Here is the value you defined for pi
This gives the numerical value of 2
, to the same accuracy as pi
|x=value||assign a value to the variable x|
|x=y=value||assign a value to both x and y|
|x=. or Clear[x]||remove any value assigned to x|
Assigning values to variables.
It is very important to realize that values you assign to variables are permanent
. Once you have assigned a value to a particular variable, the value will be kept until you explicitly remove it. The value will, of course, disappear if you start a whole new Mathematica
Forgetting about definitions you made earlier is the single most common cause of mistakes when using Mathematica
. If you set x=5
assumes that you always
to have the value 5
, until or unless you explicitly tell it otherwise. To avoid mistakes, you should remove values you have defined as soon as you have finished using them.
|• Remove values you assign to variables as soon as you finish using them.|
A useful principle in using Mathematica.
The variables you define can have almost any name. There is no limit on the length of their names. One constraint, however, is that variable names can never start
with numbers. For example, x2
could be a variable, but 2x
uses both uppercase and lowercase letters. There is a convention that built-in Mathematica
objects always have names starting with uppercase (capital) letters. To avoid confusion, you should always choose names for your own variables that start with lowercase letters.
|aaaaa||a variable name containing only lowercase letters|
|Aaaaa||a built-in object whose name begins with a capital letter|
You can type formulas involving variables in Mathematica
almost exactly as you would in mathematics. There are a few important points to watch, however.
|• x y means x times y.|
|• xy with no space is the variable with name xy.|
|• 5x means 5 times x.|
|• x^2y means (x^2) y, not x^(2y).|
Some points to watch when using variables in Mathematica.