Axial Piston Pumps Equation Help

Right, im in the process of designing an axial piston pump.

I have obtained the following formula from a text book for power output. unfortunately i dont know what units the formula requires, is anyone able to confirm what they are? Also, if anyone knows of a good resource for pump design please let me know!

right

P=2rANtan@(p2-p1)n

where

P=power
r=radius of centre of piston from axis
A=area of piston
N=number of pistons
@=swashplate angle
p2 and p1 = pressure differential
n=either rpm or revs per second - i dont know

I need the forumla to be in metric form - basically, if i use

P=Watts
r=metres
A=metres^2
p=pascals
n=rpm/rps

Will the formula be correct?

Many Thanks

Ed