Return the times of sunrise and sunset

INTERFACE:

    subroutine sunrise_sunset(latitude,declination,sunrise,sunset)

DESCRIPTION:

This functions returns the time difference between two dates in seconds. The dates are given as Julian day and seconds of that day.

USES:

    IMPLICIT NONE

INPUT PARAMETERS:

    REALTYPE, intent(in)                :: latitude,declination

OUTPUT PARAMETERS:

    REALTYPE, intent(out)               :: sunrise,sunset

REVISION HISTORY:

    Original author(s): Karsten Bolding & Hans Burchard

LOCAL VARIABLES:

    REALTYPE                  :: omega,hour