After many hours of debugging deep inside a hessian that sometimes produced weird results.

In [48]:

(-y**2 * (y - 1)) / (y**2. * (y - 1))

Out[48]:

array([[ -1.00000000e+00],

[ -1.77041643e-03],

[ 5.80863636e-04],

[ -5.37729923e-03],

[ -1.74809893e-03],

[ 2.25499819e-02],

[ 8.65999453e-03]])

y is int32

Josef