[Octave-bug-tracker] [bug #60528] betaincinv throws error for some valid inputs

[Markus Mützel]

Update of bug #60528 (project octave):

                  Status:             In Progress => Fixed                  
             Open/Closed:                    Open => Closed                 

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Follow-up Comment #6:

Fwiw, in Matlab R2021a:

>> betaincinv (1-1e-6, 3, 1)

ans =

   0.999999666666556



And according to Wolfram Alpha it should be
0.9999996666665555554938271193415336076582837792003093193653324836...
https://www.wolframalpha.com/input/?i2d=true&i=InverseBetaRegularized%281-1e-6%5C%28%2C%29+3%5C%28%2C%29+1%29

So that looks good.

The second example should be exactly 1/100 according to Wolfram Alpha:
https://www.wolframalpha.com/input/?i2d=true&i=InverseBetaRegularized%281e-6%5C%28%2C%29+3%5C%28%2C%29+1%29

In Matlab R2021a:

>> betaincinv (1-1e-6, 3, 1, "upper")

ans =

   0.010000000000096


So, we seem to be closer than Matlab both on Windows and even more so on
Linux.

I updated the reference values from Wolfram Alpha and increased the tolerance
for one of the BISTs here:
https://hg.savannah.gnu.org/hgweb/octave/rev/40157299fdeb

Closing report again.


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