[SOLVED] Map navigation (math problem)

[Mutley]

This is quite a puzzle, hopefully you can help me out! 

 

I'm trying to make a navigational map, here it is:

http://tinyurl.com/yhlxs2f

 

It's supposed to be 30x30 square, so if you navigate all the way to one side, it will stop you going any further. So the boundaries are finite.

 

What you see on screen, is a 10x10 AREA of the 30x30 box.

 

The numbers should all be unique AND when you navigate, they should stay in sequence, at the moment, they shuffle. So the 30x30 box of numbers, should never actually move, it's the 10x10 view, that is moving around instead.

 

I believe it's all down to this line that is making the numbers shuffle:

$n2=$n+($r*(2*($x_limit+5)));

 

I've attached the file to my post.

 

Thanks in advance, it has being doing my tree in!  :'(

 

 

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