Since you have specifically asked for a Fluid Head - presumably for video work - I Just bought a Manfrotto MVH500AH
(http://www.manfrotto.co.uk/lightweight-fluid-video-head-flat-base)

This is a fairly lightweight head which I have used for everything between a Sony NEX5 and a Nikon D800, even a Black Magic Ursa.

Very smooth, adjustable drag, lockable etc.

BUT you will need a suitably sturdy tripod, a cheapo twisty bendy thing just wont cut it.

Are there fluid tripod heads made for panning with a lightweight, compact camera?
I want to calculate the probability distribution for the total of a combination of dice. 

I remember that the probability of is the number of combinations that total that number over the total number of combinations (assuming the dice have a uniform distribution). 

What are the formulas for


The number of combinations total
The number of combinations that total a certain number

