!	call  reldaych(day,mo,yr,delday,delmo,delyr)   !changes day mo yr
!	change a day by # days,mo, yr, and make legal date
	subroutine reldaych(day,mo,yr,dd,dm,dy)
	implicit none
	integer nmody(0:13),day,mo,yr,dd,dm,dy,nday,mole
	data nmody /31, 31,28,31, 30,31,30, 31,31,30, 31,30,31, 31/
	call j1980(mo,day,yr,nday) !returns # days since 1/1/1980
!	dont forget to fix j1980 before 28 feb 2100 sbp
	nmody(2)=28+mod(yr-1,4)/3  !29 if leap
	if(mod(yr,100).eq.0) nmody(2)=28 !2100
	if(mod(yr,400).eq.0) nmody(2)=29 !2000
	mole=30			!default if no mo
	if(mo.gt.0) then
	 if(dm.lt.0) mole=nmody(mo-1)
	 if(dm.gt.0) mole=nmody(mo)
	endif
	nday=nday+dd+dm*mole +dy*365
	call j1980mdy(nday,mo,day,yr) !convert back daycount (1980 to..)
	return
	end