[Octave-bug-tracker] [bug #47800] gammainc(x, a, "upper") rounds down to zero if output is below eps

[Marco Caliari]

Follow-up Comment #3, bug #47800 (project octave):

I attach xcgmainc.f, a modification of slatec dgamic, which computes the
complementary incomplete Gamma functions. The modifications are

1) transformation into a subroutine (like xgmainc.f by jwe)
2) division by Gamma(A) (not present in dgamic)

It requires d9gmic (not in liboctave/cruft/slatec-fn). When invoked with call
xcgmainc(6.0d0,60.0d0,result) it gives result=6.1802e-20. Am I on the right
way for the incorporation into Octave? Because Matlab allows also
'scaledupper' and 'scaledlower', which I would like to implement. Of course,
the single version is still missing.

(file #37056)
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Additional Item Attachment:

File name: xcgmainc.f                     Size:4 KB


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