From: Arthur E. Snyder <snyder_at_slac.stanford.edu>

Date: Tue, 25 Oct 2005 21:25:57 -0700 (PDT)

Date: Tue, 25 Oct 2005 21:25:57 -0700 (PDT)

I find if I do an integral of a positive definite function I get 0 if the limits are large. E.g., a simple 1 sigma Gaussian:

root [18] g->Integral(0,5)

*(Double_t)6.26657068657750171e-01*

root [19] g->Integral(0,1000)

*(Double_t)5.47544282673530046e-24*

root [20] g->Integral(0,10000)

*(Double_t)0.00000000000000000e+00*

root [21]

This is not a very sensible or convenient behavior. It appears if the limits are set very large the interval used in the nummerical intergration are so large that the non-zero regions of the function may be missed entirely.

A bug or a feature? Certainly a nuissance when I'm trying to convolute a Gaussian with some other function using this numerical integration.

Is there perhaps some way to avoid this problem?

-Art S.

A.E. Snyder, Group EC \!c*p?/ SLAC Mail Stop #95 ((. .)) Box 4349 | Stanford, Ca, USA, 94309 '\|/` e-mail:snyder_at_slac.stanford.edu o phone:650-926-2701 _ http://www.slac.stanford.edu/~snyder BaBar FAX:650-926-2657 CollaborationReceived on Wed Oct 26 2005 - 06:26:07 MEST

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