ISDSTIME()

Fortran version: 

    INTEGER FUNCTION  ISDSTIME( JDATE )
        INTEGER   JDATE	!  Julian date (YYYYDDD)

No C version:

Summary:

ISDSTIME() returns 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.

Preconditions:

JDATE represented according to EDSS/Models-3 date and time conventions

Fortran Usage:

For Fortran-90 declarations and interface checking: 
    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
    ...

Previous: HHMMSS

Next: JDATE3

Up: Date-Time Manipulation Routines

To: Models-3/EDSS I/O API: The Help Pages