NAME:
sigma2surfacemass
PURPOSE:
calculate the product sigma_R^2 x surface-mass at R by marginalizing over velocity
INPUT:
R - radius at which to calculate the sigma_R^2 x surfacemass density (/ro)
OPTIONAL INPUT:
nsigma - number of sigma to integrate the velocities over
KEYWORDS:
romberg - if True, use a romberg integrator (default: False)
OUTPUT:
sigma_R^2 x surface-mass at R
HISTORY:
2010-03-XX - Written - Bovy (NYU)