Overflow in pdf ratio with KDE smoothing for public data with injection.

[juanma-cano-vila]

When injecting events in an analysis instance with the option kde_smoothing=True, it can happen sometimes that the kde smoothing assigns extremely low values to the bkg pdf, of the order of 1e-200 or lower. This can produce for some injected events to run in an overflow when computing the pdf ratio.

In the current implementation we have

skyllh/skyllh/analyses/i3/publicdata_ps/pdfratio.py

Lines 216 to 228 in 6704ef9

	m_nonzero_bkg = bkg_pd > 0
	m_zero_bkg = np.invert(m_nonzero_bkg)
	if np.any(m_zero_bkg):
	ev_idxs = np.where(m_zero_bkg)[0]
	self._logger.debug(
	f'For {len(ev_idxs)} events the background probability is '
	f'zero. The event indices of these events are: {ev_idxs}')
	np.divide(
	ratio,
	bkg_pd,
	where=m_nonzero_bkg,
	out=ratio)

The m_nonzero_bkg = bkg_pd > 0 is not enough when appliying kde smoothing. I suggest to change it to
m_nonzero_bkg = bkg_pd > np.finfo(np.double).resolution . This will assign this close to 0 values the same treatment as expected with no kde smoothing.