Hi all,
I am having pymc3 crash my kernel with a very simple model
with pm.Model() as model:
ps = pm.Dirichlet(‘ps’, a=np.array([1,0,0]))
counts = pm.Multinomial(“counts”,n=30,p=ps,observed=[29,1,0])
trace=pm.sample(1000,tune=500)
If I impose only one job (chains=1) it does not crash the kernel but gives a error “BadInitialEnergy”.
Does anyone have any idea of what could be going on?
Hi Tiago,
Yeah, it’s actually a good thing it crashes: the concentration vector of the Dirichlet has to be strictly positive, but you entered zeros at the second and third positions, so the log probability is -inf, making the model impossible to sample from.
Here is a post about Dirichlet and Multinomial distributions by @clausherther – that should help you 
Hope this helps 
Thanks!! I totally overlooked that…