Q:

How can I group form elements

I got this form:
<form method="post" action="" accept-charset="utf-8"> 
<p>
  <label>first_field</label><br />
  <input type="text" id="first_field" name="points[]" /><br />
  <input type="radio" value="inside" name="group_1" checked /><br />
  <input type="radio" value="outside" name="group_1"><br />
</p>
<p>
  <label>second_field</label><br />
  <input type="text" id="second_field" name="points[]" /><br />
  <input type="radio" value="inside" name="group_2" checked /><br />
  <input type="radio" value="outside" name="group_2"><br />
</p>
</form>

What i want to accomplish is to check if inside or outside is checked, if outside i checked the multiply points for the given text input by 1,5.  BTW this needs to be calculated in PHP. 
How can I do that? 
UPDATE
Array
(
[bonus] => Array
    (
        [points] => Array
            (
                [0] => 0
                [1] => 0
                [2] => 0
                [3] => 0
                [4] => 0
                [5] => 0
                [6] => 0
                [7] => 0
                [8] => 0
                [9] => 0
                [10] => 0
                [11] => 0
                [12] => 0
                [13] => 0
                [14] => 0
            )

        [group] => Array
            (
                [0] => inside
                [1] => outside
                [2] => outside
                [3] => inside
                [4] => inside
                [5] => inside
                [6] => inside
                [7] => inside
                [8] => outside
                [9] => inside
                [10] => inside
                [11] => inside
                [12] => outside
                [13] => inside
                [14] => inside
            )

    )

)

Above is the result of print_r($_POST)
Now ho do I compare/pare The points array with the Group array so:
points[0] gets "connected" to group[0] etc.? 

A:

As it turns out, you can group fields using HTML forms.  Check out this code here: (specifically note the name attributes)
<form method="post" action="" accept-charset="utf-8">
<p>
  <label>first_field</label><br />
  <input type="text" id="first_field" name="field[1][points]" /><br />
  <input type="radio" value="inside" name="field[1][group]" checked /><br />
  <input type="radio" value="outside" name="field[1][group]"><br />
</p>
<p>
  <label>second_field</label><br />
  <input type="text" id="second_field" name="field[2][points]" /><br />
  <input type="radio" value="inside" name="field[2][group]" checked /><br />
  <input type="radio" value="outside" name="field[2][group]"><br />
</p>
</form>

Without filling anything in, this will yield a POST array like this:
Array
(
    [field] => Array
        (
            [1] => Array
                (
                    [points] => 
                    [group] => inside
                )

            [2] => Array
                (
                    [points] => 
                    [group] => inside
                )

        )
)

I hope this answered your question, it's a neat little trick I haven't really seen many others discuss.  One thing to note is that you'll need to manually specify an ID number in that any set of brackets.  You can only use [] as the last set of brackets.