NAME:
vmomentsurfacemass
PURPOSE:
calculate the an arbitrary moment of the velocity distribution at R times the surfacmass
INPUT:
R - radius at which to calculate the moment(/ro)
n - vR^n
m - vT^m
OPTIONAL INPUT:
nsigma - number of sigma to integrate the velocities over
KEYWORDS:
romberg - if True, use a romberg integrator (default: False)
deriv= None, ‘R’, or ‘phi’: calculates derivative of the moment wrt R or phi
OUTPUT:
<vR^n vT^m x surface-mass> at R
HISTORY:
2011-03-30 - Written - Bovy (NYU)
