`red'
-----

red(RAT)
     :: RAT ʬ.

RETURN
     ͭ
RAT
     ͭ

   * Asir ͭʬ˼ưŪ˹Ԥ. , ͭˤĤƤ
     ʬϹԤ, ʬϥ桼ꤷʤ¤Ԥʤ. ʬ
     ޥɤ red Ǥ.
   * EZGCD ˤ RAT ʬ, ʬʬ.
   * Ϥͭʬ¿༰, Ʒ GCD  1 ¿
     ༰Ǥ. ʬҤˤĤƤ¿༰ȤʤȤϸ¤ʤ.
   * GCD ѽŤ黻ʤΤ, ¾ˡǽ붦̰Ҥϲǽʸ¤
     Τ˾ޤ. ޤ, ʬ, ʬҤ礭ʤäƤΤȡθ
     ӽФ, ˻֤ݤ礬¿. ͭ黻Ԥ, 
     ˤ, ʬԤɬפ.

     [0] (x^3-1)/(x-1);
     (x^3-1)/(x-1)
     [1] red((x^3-1)/(x-1));
     x^2+x+1
     [2] red((x^3+y^3+z^3-3*x*y*z)/(x+y+z));
     x^2+(-y-z)*x+y^2-z*y+z^2
     [3] red((3*x*y)/(12*x^2+21*y^3*x));
     (y)/(4*x+7*y^3)
     [4] red((3/4*x^2+5/6*x)/(2*y*x+4/3*x));
     (9/8*x+5/4)/(3*y+2)


     `nm', `dn', `gcd', `ptozp'

