NAME:
vmomentsurfacemass
PURPOSE:
calculate the an arbitrary moment of the velocity distribution at (R,phi) times the surfacmass
INPUT:
R - radius at which to calculate the moment(/ro)
phi= azimuth (rad unless deg=True)
n - vR^n
m - vT^m
t= time at which to evaluate the DF (can be a list or ndarray; if this is the case, list needs to be in descending order and equally spaced)
nsigma - number of sigma to integrate the velocities over (based on an estimate, so be generous, but not too generous)
deg= azimuth is in degree (default=False)
epsrel, epsabs - scipy.integrate keywords (the integration calculates the ratio of this vmoment to that of the initial DF)
grid= if set to True, build a grid and use that to evaluate integrals; if set to a grid-objects (such as returned by this procedure), use this grid; if this was created for a list of times, moments are calculated for each time
gridpoints= number of points to use for the grid in 1D (default=101)
returnGrid= if True, return the grid object (default=False)
hierarchgrid= if True, use a hierarchical grid (default=False)
nlevels= number of hierarchical levels for the hierarchical grid
print_progress= if True, print progress updates
integrate_method= orbit.integrate method argument
deriv= None, ‘R’, or ‘phi’: calculates derivative of the moment wrt R or phi onnly with grid options
OUTPUT:
<vR^n vT^m x surface-mass> at R,phi
COMMENT:
grid-based calculation is the only one that is heavily tested (although the test suite also tests the direct calculation)
HISTORY:
2011-03-30 - Written - Bovy (NYU)