logical function leapyear (nyear)
c This function decides whether a particular year is a leap year
c Rule 1: Years not exactly divisible by four are not leap years
c Rule 2: Years not exactly divisible by one hundred are leap years
c Rule 3: Years not exactly divisible by four hundred are not leapyears
c Years exactly divisible by four hundred are leapyears
logical test
test(n) = (nyear/n)*n .eq. nyear
leapyear = test(4)
if (leapyear) then
leapyear = .not.test(100)
if (.not.leapyear) leapyear = test(400)
end if
return
end