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

utrunc(P,D)
udecomp(P,D)
ureverse(P)
     :: Operations on polynomials

RETURN
     univariate polynomial or list of univariate polynomials

P
     univariate polynomial

D
     non-negative integer

   * Let X be the variable of P. Then P can be decomposed as P =
     P1+x^(D+1)P2, where the degree of P1 is less than or equal to D.
     Under the decomposition, `utrunc()' returns P1 and  `udecomp()'
     returns [P1,P2].

   * Let E be the degree of P and P[I] the coefficient of P at degree
     I. Then `ureverse()' returns P[E]+P[E-1]x+....

     [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

References
     *Note `udiv urem urembymul urembymul_precomp ugcd': udiv urem
     urembymul urembymul_precomp ugcd.

