`vars'
------

vars(OBJ)
     :: OBJ $B$K4^$^$l$kJQ?t$N%j%9%H(B.

RETURN
     $B%j%9%H(B

OBJ
     $BG$0U(B

   * $BM?$($i$l$?<0$K4^$^$l$kJQ?t$N%j%9%H$rJV$9(B.

   * $BJQ?t=g=x$N9b$$$b$N$+$i=g$KJB$Y$k(B.

     [0] vars(x^2+y^2+a^2);
     [x,y,a]
     [1] vars(3/abc+2*xy/efg);
     [abc,xy,efg]
     [2] vars([x,y,z]);
     [x,y,z]

$B;2>H(B
     *Note `var': var, *Note `uc': uc, *Note `ord': ord.

