`utrunc', `udecomp', `ureverse'
-------------------------------

utrunc(P,D)
udecomp(P,D)
ureverse(P)
     :: $BB?9`<0$KBP$9$kA`:n(B

RETURN
     $B0lJQ?tB?9`<0$"$k$$$O0lJQ?tB?9`<0$N%j%9%H(B

P
     $B0lJQ?tB?9`<0(B

D
     $BHsIi@0?t(B

   * P $B$NJQ?t$r(B x $B$H$9$k(B. $B$3$N$H$-(B P = P1+x^(d+1)P2 (P1 $B$N<!?t$O(B D
     $B0J2<(B) $B$HJ,2r$G$-$k(B. `utrunc()' $B$O(B P1 $B$rJV$7(B, `udecomp()' $B$O(B
     [P1,P2] $B$rJV$9(B.

   * P $B$N<!?t$r(B E $B$H$7(B, I $B<!$N78?t$r(B P[I] $B$H$9$l$P(B, `ureverse()' $B$O(B
     P[E]+P[E-1]x+... $B$rJV$9(B.

     [132] utrunc((x+1)^10,5);
     252*x^5+210*x^4+120*x^3+45*x^2+10*x+1
     [133] udecomp((x+1)^10,5);
     [252*x^5+210*x^4+120*x^3+45*x^2+10*x+1,x^4+10*x^3+45*x^2+120*x+210]
     [134] ureverse(3*x^3+x^2+2*x);
     2*x^2+x+3

$B;2>H(B
     *Note `udiv urem urembymul urembymul_precomp ugcd': udiv urem
     urembymul urembymul_precomp ugcd.

