Primal Spire Applet in Java
This is an app I wrote for an effective programming paper at university a couple of years ago.
What it is:
A picture made by counting all pixels in a spiral pattern and making all the prime numbered
pixels a different colour (I used black for primes and blue for all other numbers).
This is the result:
The way it works is by starting at the centre pixel, colouring it blue (1 is not a prime number),
going down one pixel and colouring it black (as 2 is a prime), then going right one pixel and
colouring it black (3 is prime), then up one pixel (4 = blue), up one more pixel (5 = black),
left one pixel (6 = blue), left one more pixel (7 = black), then down one pixel (blue)... etc.
I hope that makes sense.
You can make the spire as big as you like. It currently goes to one million pixels. It's
really easy to modify the colours too if you don't like them.
