template<class eventListType, class... pdfTypes>
class AmpGen::SumPDF< eventListType, pdfTypes >
A pdf with a probability of the form
\[ P(\psi) = \sum_{j} \mathcal{P}_j (\psi),
\]
where \( \mathcal{P}_j(\psi) \) are some normalised probability density functions as a function of position in the phase space \( \psi \) , and the sum is over the different terms, typically a signal term and then a number of background terms. The pdf is also equipped with a log-likelihood of the form:
\[ -2 \mathcal{L} = - 2 \sum_{i} \log \left( \sum_{j} \mathcal{P}_j \left(\psi_i\right) \right)
\]
and the sum over \( i \) is over some dataset. This combined functionality is largely historical and the two roles should be separated at some point in the future. The sum is variadically unrolled at compile time, i.e. the wrapper is the same for 1..N pdfs. The unrolling should be properly inlined, hence N can be reasonably large with out afflicting either compile time or binary size. It isn't primarily used as PDF, as its primary function is as a likelihood via function getVal(). Typically constructed using either the make_pdf helper function or make_likelihood helper function.
Definition at line 43 of file SumPDF.h.
