(49G) Convert Modern 24hr Clock Time to Roman Hours Time (starting in 263 BC?)

[Gerald H]

In the Good Old Days when people were more sensible & natural, time was a different matter from now & Roman Hours went by the Sun, day starting at sunrise & night starting at sunset, & to be fair (as one of the Gods might not like being duped), day & night had to have the same number of hours, namely 12, resulting in day & night hours being differently long (except at the Equinoxes), the lengths also varying with the time of year.

The programme below converts modern clock time input in 24hr & decimal parts of hours to the Roman standard (from 263 BC on) -

https://en.wikipedia.org/wiki/Roman_timekeeping

NB The Roman decimal part is not decimal but minutes & seconds, which I have assumed varied in length just as did the hours - should my assumption prove false, clarification welcome on how the Romans actually dealt with parts of hours.

Store time of sunrise in S.UP eg 7.27

& time of sunset in S.Dwn eg 16.49

enter time of day, eg 18.5

run the programme

returns

N:1.3755 (FIX 4)

the "N" tag representing night, you'll see a "D" for day.

Code:

« DUP S.UP > OVER
S.DWN < AND
  IF
  THEN S.UP -
12. S.DWN S.UP
- / * "D"
  ELSE DUP S.UP <
    IF
    THEN 24. +
    END S.DWN – 12.
S.UP 24. + S.DWN - /
* "N"
  END SWAP →HMS
SWAP →TAG
»