How do I calculate altitude and azimuth of sun?

Question

I'd like to calculate the position of the sun on a given date/time/position on earth?

How would I calculate this? Or the time of sunrise/sunset? Or where can I find information about calculating the sun movement?

Answer 1

This is a good resource. I've used it ported to php.

EDIT

I have uploaded the snippet in php here. Might need some cleanup, but is a direct translation from resource above.