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[Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Li
From: |
Markus Mützel |
Subject: |
[Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions |
Date: |
Fri, 5 Aug 2022 02:27:27 -0400 (EDT) |
Follow-up Comment #26, bug #49091 (project octave):
The negative zero seems to be the cause of the issue indeed. Thank you all for
tracking this down. I didn't know that `-10i` in Octave actually meant
`-(0,10)` as opposed to `(0,-10)`.
With a modified version of the test program in comment #15, I see:
$ ./test-acosh.exe
x = 0.0000000000000000e+00
y = 1.0000000000000000e+01
cacosh(+x+1i*y) = 2.9982229502979698 + 1.5707963267948966i
cacosh(+x-1i*y) = 2.9982229502979698 + -1.5707963267948966i
cacosh(-x-1i*y) = 2.9982229502979760 + -1.5707963267948966i
std::acosh(+x+1i*y) = 2.9982229502979698 + 1.5707963267948966i
std::acosh(+x-1i*y) = 2.9982229502979698 + -1.5707963267948966i
std::acosh(-x-1i*y) = 2.998222950297976 + -1.5707963267948966i
That could probably be solved by using symmetries of the function also for the
default implementation in MinGW's CRT (not only for large input values).
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- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, (continued)
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Rik, 2022/08/03
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Nicholas Jankowski, 2022/08/03
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Markus Mützel, 2022/08/03
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Rik, 2022/08/03
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Markus Mützel, 2022/08/04
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, John W. Eaton, 2022/08/04
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Nicholas Jankowski, 2022/08/04
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, John W. Eaton, 2022/08/04
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Nicholas Jankowski, 2022/08/04
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Rik, 2022/08/04
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions,
Markus Mützel <=
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Markus Mützel, 2022/08/05
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Markus Mützel, 2022/08/07
- [Octave-bug-tracker] [bug #49091] MinGW std::acosh less accurate than Linux versions, Markus Mützel, 2022/08/28