`fctr', `sqfr'
--------------

fctr(POLY)
     :: POLY Ҥʬ򤹤.
sqfr(POLY)
     :: POLY ̵ʿʬ򤹤.

RETURN
     ꥹ
POLY
     ͭ¿༰

   * ͭ¿༰ POLY ʬ򤹤. `fctr()' ϴʬ,
     `sqfr()' ̵ʿʬ.
   * ̤ [[,1],[,ʣ],...] ʤꥹ.
   *   Ƥ ^ʣ Ѥ POLY .
   *  , (POLY/) , ,  GCD  1 Ȥʤ
     ¿༰ˤʤ褦ФƤ. (`ptozp()' )

     [0] fctr(x^10-1);
     [[1,1],[x-1,1],[x+1,1],[x^4+x^3+x^2+x+1,1],[x^4-x^3+x^2-x+1,1]]
     [1] fctr(x^3+y^3+(z/3)^3-x*y*z);
     [[1/27,1],[9*x^2+(-9*y-3*z)*x+9*y^2-3*z*y+z^2,1],[3*x+3*y+z,1]]
     [2] A=(a+b+c+d)^2;
     a^2+(2*b+2*c+2*d)*a+b^2+(2*c+2*d)*b+c^2+2*d*c+d^2
     [3] fctr(A);
     [[1,1],[a+b+c+d,2]]
     [4] A=(x+1)*(x^2-y^2)^2; 
     x^5+x^4-2*y^2*x^3-2*y^2*x^2+y^4*x+y^4
     [5] sqfr(A);
     [[1,1],[x+1,1],[-x^2+y^2,2]]
     [6] fctr(A);
     [[1,1],[x+1,1],[-x-y,2],[x-y,2]]


     `ufctrhint'

