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

[Mattias Engdegård]

12 jan. 2021 kl. 17.28 skrev Basil L. Contovounesios <contovob@tcd.ie>:

> 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")