Model behavior

Model class

A model can be normalized or not and has three different methods to access it's underlying function

Normalization

If a model is normalized, the obs Space will be taken automatically as normalization range if no explicit Space is given to the "normalization keyword (WIP).

Normalization means that the integral over the norm range is one. This is done column wise in case of a N-dim function.

Methods

There are three methods which fulfill similar needs, pdf, value and func. (It is possible that in future versions one or more will be dropped). The table shows the return whether it is normalized ("norm") or not ("non-norm") depending on whether the model is normed ("yes"/"no") and on which of the three function is called.

normed	pdf	value	func
yes	norm	norm	non-norm
no	error	non-norm	non-norm

Rational for the functions

• pdf serves the purpose to guarantee a normalized model and does a simple check if the model is normed. E.g. for building a likelihood, a PDF is required.
• value allows to be agnostic on the normalization and should be used whenever the normalization is not strictly required or "forbidden"
• func is the unnormalized function. While in general value should be preferred, sometimes intentionally the unnormalized value of the model is required. It somewhat replaces the unnormalized_pdf and should, in future, be used internally (?).