external ERF "./erf_sub_ncl.so"
begin
      nmax = 4
      x    = new ( nmax, "double")
      x(0) = 0.d0    ; erf(0)   = 0
      x(1) = 100d0   ; erf(inf) = 1
      x(2) = 0.8d0
      x(3) = 0.1d0

      xresult = -1d20

      do n=0,nmax-1
         ERF::derrf( x(n), xresult )
         print (n+"  x="+x(n)+ "  xresult="+xresult )
      end do

      zresult = -1d20

      x(0) = -100d0  ; erfc(-inf)  = 2
      x(1) = 0d0     ; erfc(0)     = 1
      x(2) = 100d0   ; erfc(inf)   = 0
      x(3) = 0.5d0   
      do n=0,nmax-1
         ERF::derrcf(0, x(n) ,zresult )
         print (n+"  x="+x(n)+  "  zresult="+zresult )
      end do
end