[Rivet] Fwd: FourMomentum mass

Hendrik Hoeth hendrik.hoeth at cern.ch
Thu Nov 11 00:32:39 GMT 2010


Thus spake Sercan Sen (Sercan.Sen at cern.ch):

> And, please can somebody explain why we have those values (NaN) ?

Photons tend to have a fairly low rest mass, both in nature and in Monte
Carlo. Combine this with the fact that computer have a limited numerical
accuracy, and you get sqrt(small_negative_number_instead_of_zero). At
least from time to time. Guess we should catch that. In fact I thought
we had already fixed this several months ago.

Cheers,

    Hendrik

-- 
One doesn't discover new lands without consenting to lose
sight of the shore for a very long time.    -- André Gide


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