# galpy.df.streamdf.freqEigvalRatio¶

streamdf.freqEigvalRatio(isotropic=False)[source]

NAME:

freqEigvalRatio

PURPOSE:

calculate the ratio between the largest and 2nd-to-largest (in abs) eigenvalue of sqrt(dO/dJ^T V_J dO/dJ) (if this is big, a 1D stream will form)

INPUT:

isotropic= (False), if True, return the ratio assuming an isotropic action distribution (i.e., just of dO/dJ)

OUTPUT:

ratio between eigenvalues of fabs(dO / dJ)

HISTORY:

2013-12-05 - Written - Bovy (IAS)