NAME:
sigangledAngle
PURPOSE:
calculate the dispersion in the perpendicular angle at a given angle
INPUT:
dangle - angle offset along the stream
assumeZeroMean= (True) if True, assume that the mean is zero (should be)
smallest= (False) calculate for smallest eigenvalue direction rather than for middle
simple= (False), if True, return an even simpler estimate
OUTPUT:
dispersion in the perpendicular angle at this angle
HISTORY:
2013-12-06 - Written - Bovy (IAS)