date_1 = interval(1)
date_1 = date_1 + intv_1
if ((date_1 .gt. 0) .and.
date_1 = date_1 - 1
di = fac*date_1
integer date_1,date_2
date_1 = 0
date_1 = date(1)
date_1 = -date(1)
yy = date_1/10000
mm = mod(date_1/100,100)
dd = mod(date_1,100)
dd = date_1
integer date_1