implicit double precision (a-h,o-z)
      parameter(imax=2)
      dimension a(imax),b(imax),c(imax),r(imax),v(imax)

      do 10 i=1,imax
         a(i) = -20.0
         b(i) = 30.0
         c(i) = -20.0
   10 continue
      r(1) = -10.0
      r(2) = 40.0
      call tridag(a,b,c,r,imax)
      do 100 i=1,imax
         v(i) = r(i)
	 write (6,*) v(i)
  100 continue 
      stop
      end