integer function yearlen(iy)
  !  NAME          FUNCTION  CONTROL     C.LIB.TIME  SBP         99.01.21  
  !    l=yearlen(iy)           !days in iy

  implicit none

  integer :: iy
  if(mod(iy,4).ne.0) goto 999
  yearlen=366
  if(mod(iy,100).ne.0) return     !centuries usually not leap,            
  if(mod(iy,400).eq.0) return     !but 2000,2400... are
999 yearlen=365
  return
end function yearlen