11_creating_functions.qmd

# Creating Functions

Another very nice feature of **[R]{.sans-serif}** is the ability to
easily write your own programs and functions. We will begin by creating
a new function called `add.machine` that will simply sum two numbers:

`add.machine `$=$` function(num1, num2){`\
`result `$=$` num1 `$+$` num2`\
`return(result)`\
`}`

The following are important components of the code above:

-   `add.machine` is the name of the newly created object

-   `function` declares that `add.machine` will be a function

-   `num1` and `num2` are the arguments that `add.machine` will take as
    input

-   The body of the function is enclosed in curly braces

-   `return` (is optional) but specifies the output that is returned
    from the function

Let's test out the newly created function

`> add.machine`

`> add.machine(3,5)`

What happens if we don't specify valid arguments?

`> add.machine(3)`

`> add.machine(3, "Hi")`