NAME:
rl
PURPOSE:
calculate the radius of a circular orbit of Lz
INPUT:
Pot - Potential instance or list thereof
lz - Angular momentum
OUTPUT:
radius
HISTORY:
2012-07-30 - Written - Bovy (IAS@MPIA)
NOTE:
seems to take about ~0.5 ms for a Miyamoto-Nagai potential; ~0.75 ms for a MWPotential