`nm', `dn'
----------

nm(RAT)
     :: RAT $B$NJ,;R(B.

dn(RAT)
     :: RAT $B$NJ,Jl(B.

RETURN
     $B@0?t$^$?$OB?9`<0(B

RAT
     $BM-M}?t$^$?$OM-M}<0(B

   * $BM?$($i$l$?M-M}?t$^$?M-M}<0$NJ,;R5Z$SJ,Jl$rJV$9(B.

   * $BM-M}?t$N>l9g(B, $BJ,Jl$O>o$K@5$G(B, $BId9f$OJ,;R$,;}$D(B.

   * $BM-M}<0$N>l9g(B, $BC1$KJ,Jl(B, $BJ,;R$r<h$j=P$9$@$1$G$"$k(B.
     $BM-M}<0$KBP$7$F$O(B, $BLsJ,$O<+F0E*$K$O9T$o$l$J$$(B. `red()'
     $B$rL@<(E*$K8F$S=P$9I,MW$,$"$k(B.

     [2] [nm(-43/8),dn(-43/8)];
     [-43,8]
     [3] dn((x*z)/(x*y));
     y*x
     [3] dn(red((x*z)/(x*y)));
     y

$B;2>H(B
     *Note `red': red.

