program fringe
	character name*2(30),bigname*12
	data name/
	1 '01','03','05','07','09',
	1 '11','13','15','17','19',
	1 '21','23','25','27','29',
	1 '31','33','35','37','39',
	1 '41','43','45','47','49',
	1 '51','53','55','57','59'/
		do ii=1,59,2
                ihoo= (ii+1)/2
		bigname='fringe'//name(ihoo)//'.dat'
		call delold(bigname)
		open(1,file=bigname,status='new')
		d=1.0+ii/100.
		per=10./(2*d)
		freq=2*3.14159/per
			do i=4000,20000
			wl=i/100.
			sig=10000./wl
			y=cos(sig*freq)
			write(1,*)wl,y
			enddo
		enddo
	end
        subroutine delold(name)
        character*30 name
        logical ex
        inquire(file=name,exist=ex)
        if(ex.eq..true.)then
        open(10,file=name,status='old')
        close(10,status='delete')
        endif
        return
        end