Subject: Re: bug#45818: 28.0.50; Test solar-sunrise-sunset fails

From: Mattias Engdegård <[email-masked]>
Date: Tue, 12 Jan 2021 19:50:33 +0100

12 jan. 2021 kl. 17.28 skrev Basil L. Contovounesios <[email-masked]>:

> At that point, sunrise-sunset has the following value:
> 
>  ((6.266666667535901 #1="IST") (16.716666667722166 #1#) "10:26")

On my machines (sitting in CET) it is

((7.2666666666045785 "IST") (17.716666666790843 "IST") "10:26")

and the time zone names don't seem to matter for the numerical results today, but maybe it depends on when it's run. In any case we should probably use something less ambiguous than IST (which is apparently also used for Israeli standard time).

I've been unable to reproduce your results but am not sure how to go about doing so exactly; running with TZ=GMT does not alter the results.

Could you try tracking down the origin of those numbers? Here is a trace of some of the relevant functions on my machines:

1 -> (solar-sunrise-sunset (12 30 2020))
| 2 -> (solar-exact-local-noon (12 30 2020))
| | 3 -> (solar-julian-ut-centuries (12 30 2020))
| | 3 <- solar-julian-ut-centuries: 0.2099520876112252
| 2 <- solar-exact-local-noon: ((12 30 2020) 6.9905251059993585)
| 2 -> (solar-julian-ut-centuries (12 30 2020))
| 2 <- solar-julian-ut-centuries: 0.2099520876112252
| 2 -> (solar-sidereal-time 0.2099520876112252)
| 2 <- solar-sidereal-time: 6.592887211896198
| 2 -> (solar-sunrise-and-sunset (0.2099520876112252 6.9905251059993585) 1.0 75.8 0)
| 2 <- solar-sunrise-and-sunset: (6.5198219809993585 18.46122823099936 11.941406250000002)
| 2 -> (solar-sunrise-and-sunset (0.2099520876112252 6.9905251059993585) 26.9 75.8 -0.61)
| 2 <- solar-sunrise-and-sunset: (7.2698219809993585 17.71122823099936 10.441406250000002)
| 2 -> (dst-adjust-time (12 30 2020) 7.2698219809993585)
| 2 <- dst-adjust-time: ((12 30 2020) 7.2666666666045785 "IST")
| 2 -> (dst-adjust-time (12 30 2020) 17.71122823099936)
| 2 <- dst-adjust-time: ((12 30 2020) 17.716666666790843 "IST")
| 2 -> (calendar-date-equal (12 30 2020) (12 30 2020))
| 2 <- calendar-date-equal: t
| 2 -> (calendar-date-equal (12 30 2020) (12 30 2020))
| 2 <- calendar-date-equal: t
1 <- solar-sunrise-sunset: ((7.2666666666045785 #1="IST") (17.716666666790843 #1#) "10:26")