Table 1:

Features for Representing an Experimental and Theoretical Envelope Pair.

feature	description
Ie(p)	normalized intensity of a peak p in the experimental envelope
It(p’)	normalized intensity of a peak p’ in the theoretical envelope
Sx(p,p’)	piecewise function of the m/z value similarity of an experimental peak p and its matched theoretical peak p’
Dy(p,p’)	intensity difference between an experimental peak p and its matched theoretical peak p’
RE	log ratio of the highest peak intensity in the theoretical envelope and the baseline intensity of the spectrum