Kay,
Thanks. I have been using Sarah Reichelt's Date & Time Library, which contains
these functions by Mark Wieder. I actually didn't realize they were under
copyright, but I see that now.
It says something nice about LC that this code is 10 years old and still valid
and valuable.
- Charles
-- dateTimeToJulian(pYear, pMonth, pDate, [pHour], [pMins], [pSecs])
--
-- dateTimeToJulian()
-- dateTimeToJulian(2004,3,22)
-- dateTimeToJulian(2004,3,22,12,2)
-- dateTimeToJulian(2004,3,22,12,5,45)
--
-- This function returns the date and time in Julian date format.
-- If no date is specified, it will use the current date.
-- If supplied, the date must be in date items format: year, month, day, hour,
minutes, seconds
-- This is because the internal date conversions may not work for early dates.
-- The time parameters are optional and seconds need not be specified.
--
-- Julian dates (abbreviated JD) are simply a continuous count of days and
fractions
-- since noon Universal Time on January 1, 4713 BCE (on the Julian calendar).
-- Almost 2.5 million days have transpired since this date.
-- Julian dates are widely used as time variables within astronomical software.
-- Typically, a 64-bit floating point (double precision) variable can represent
-- an epoch expressed as a Julian date to about 1 millisecond precision.
-- Note that the time scale that is the basis for Julian dates is Universal
Time,
-- and that 0h UT corresponds to a Julian date fraction of 0.5.
--
-- It is assumed that 7-day weeks have formed an uninterrupted sequence since
ancient times.
-- Thus, the day of the week can be obtained from the remainder of the division
of
-- the Julian date by 7.
--
-- This function is copyright 2004 Mark Wieder and Ah, Software
--
function dateTimeToJulian pYear, pMonth, pDate, pHour, pMins, pSecs
if the paramcount < 3 then
put the seconds into tNow
convert tNow to dateItems
put item 1 of tNow into pYear
put item 2 of tNow into pMonth
put item 3 of tNow into pDate
put item 4 of tNow into pHour
put item 5 of tNow into pMins
put item 6 of tNow into pSecs
end if
if pHour is empty then put 0 into pHour
if pMins is empty then put 0 into pMins
if pSecs is empty then put 0 into pSecs
-- calculate date part of Julian number
put 100 * pYear + pMonth - 190002.5 into extra
put 367 * pYear into julianDate
subtract trunc(7.0 * (pYear + trunc((pMonth + 9) / 12)) / 4) from julianDate
add trunc(275 * pMonth / 9 ) to julianDate
add pDate to julianDate
-- now add the time as a fractional day
add (pHour + (pMins + pSecs / 60) / 60) / 24 to julianDate
add 1721013.5 to julianDate
subtract .5 * extra / abs(extra) from julianDate
-- compensate for the fact the UTC starts at noon
add .5 to julianDate
return julianDate
end dateTimeToJulian
-- JulianToDateTime(pJulian)
--
-- JulianToDateTime(2453086.5)
-- JulianToDateTime(2453087.001389)
-- JulianToDateTime(2453087.003993)
--
-- This function returns the date in short English date format.
-- If the supplied Julian time includes a time component,
-- it returns the time in either long or short 24 hour format,
-- depending on whether the seconds are zero or not.
-- See dateTimeToJulian for more notes about Julian dates.
--
-- This function is copyright 2004 Mark Wieder and Ah, Software
--
function JulianToDateTime pJulian
put trunc(pJulian + .5) into jd0
if (jd0 < 2299161) then
put jd0 + 1524 into c
else
put trunc((jd0 - 1867216.25) / 36524.25) into b
put jd0 + (b - trunc(b/4)) + 1525 into c
end if
put trunc((c - 122.1)/365.25) into d
put 365 * d + trunc(d/4) into e
put trunc((c-e) / 30.6001) into f
put trunc(c - e + .5) - trunc(30.6001 * f) into tDate
put f - 1 - 12 * trunc(f/14) into tMonth
put d - 4715 - trunc((7 + tMonth) /10) into tYear
put 24 * (pJulian + .5 - jd0) into tempHour
put trunc(tempHour * 60 + .5) / 60 into tHour
put trunc(tHour) into tHour
put (60 * (tempHour - tHour)) into tempMin
put trunc(tempMin) into tMin
put round(60 * (tempMin - tMin)) into tSec
if tHour < 10 then put "0" before tHour
if tMin < 10 then put "0" before tMin
if tSec < 10 then put "0" before tSec
if tHour = 0 and tMin = 0 and tSec = 0 then
put tMonth & "/" & trunc(tDate) & "/" & tYear into tResult
else if tSec = 0 then
put tMonth & "/" & trunc(tDate) & "/" & tYear && tHour & ":" & tMin into
tResult
else
put tMonth & "/" & trunc(tDate) & "/" & tYear && tHour & ":" & tMin & ":"
& tSec into tResult
end if
return tResult
end JulianToDateTime()
On 23 Aug 2014, at 3:28 AM, Kay C Lan <lan.kc.macm...@gmail.com> wrote:
> Nope, but this will help you calculate the Julian Date Number, which
> you'll need:
>
> put the date into tDate
> convert tDate from date to dateItems
> if ((item 2 of tDate = 1) or (item 2 of tDate = 2)) then
> put 1 into tDay
> else
> put 0 into tDay
> end if
> put item 1 of tDate + 4800 - tDay into tYear
> put item 2 of tDate + (12 * tDay) - 3 into tMonth
> put item 3 of tDate + \
> ((153 * tMonth + 2) div 5) + \
> (365 * tYear) + \
> (tYear div 4) - \
> (tYear div 100) + \
> (tYear div 400) - \
> 32045 into tJDN
>
> On Sat, Aug 23, 2014 at 7:46 AM, Charles E Buchwald <char...@buchwald.ca>
> wrote:
>> Hi List People,
>> Does anyone know of an LC version of sunrise/sunset and twilight
>> calculations?
>> [snip...]
--
Charles E. Buchwald
CEO/Director General
Museografica Digital
http://digital.museografica.com
Mac OSX 10.9.4, LC 6.6.2 Commercial
LC Developer Tools: http://buchwald.ca/developer-tools/
Email Notice: http://wp.me/P3aT4d-33
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