INTEGER FUNCTION ISDSTIME( JDATE ) INTEGER JDATE ! Julian date (YYYYDDD)
TRUE
if and only if
daylight savings time is in effect for the
Julian date JDATE
,
using the Zeller's-congruence algorithm to find the start and end
for DST. Handles both pre-2007 (starts first Sunday in April, ends
last Sunday in October) and 2007-and-after (second Sunday in March,
first Sunday in November).
See also subroutines DAYMON(), HHMMSS(), JULIAN(), MMDDYY(), WKDAY(), and DT2STR() as well as EDSS/ Models-3 date-time manipulation programs gregdate and juldate.
USE M3UTILIO
... ... LOGICAL ISDSTIME INTEGER JDATE ... IF ( ISDSTIME( JDATE ) ) THEN C ...daylight savings time in effect ELSE C ...daylight savings time NOT in effect END IF ...
Up: Date-Time Manipulation Routines
To: Models-3/EDSS I/O API: The Help Pages