NAME:
vxvyvz_to_galcencyl
PURPOSE:
transform velocities in XYZ coordinates (wrt Sun) to cylindrical Galactocentric coordinates for velocities
INPUT:
vx - U
vy - V
vz - W
X - X in Galactocentric rectangular coordinates
Y - Y in Galactocentric rectangular coordinates
Z - Z in Galactocentric rectangular coordinates
vsun - velocity of the sun in the GC frame ndarray[3]
galcen - if True, then X,Y,Z are in cylindrical Galactocentric coordinates rather than rectangular coordinates
OUTPUT:
vRg, vTg, vZg
HISTORY:
2010-09-24 - Written - Bovy (NYU)