`dp_hm', `dp_ht', `dp_hc', `dp_rest'
------------------------------------

dp_hm(DPOLY)
     :: Gets the head monomial.

dp_ht(DPOLY)
     :: Gets the head term.

dp_hc(DPOLY)
     :: Gets the head coefficient.

dp_rest(DPOLY)
     :: Gets the remainder of the polynomial where the head monomial is
     removed.

RETURN
     `dp_hm()', `dp_ht()', `dp_rest()' : distributed polynomial
     `dp_hc()' : number or polynomial

DPOLY
     distributed polynomial

   * These are used to get various parts of a distributed polynomial.

   * The next equations hold for a distributed polynomial P.
    `P = dp_hm(P) + dp_rest(P)'

    `dp_hm(P) = dp_hc(P) dp_ht(P)'

     [87] dp_ord(0)$
     [88] X=ptozp((a46^2+7/10*a46+7/48)*u3^4-50/27*a46^2-35/27*a46-49/216)$
     [89] T=dp_ptod(X,[u3,u4,a46])$
     [90] dp_hm(T);
     (2160)*<<4,0,2>>
     [91] dp_ht(T);
     (1)*<<4,0,2>>
     [92] dp_hc(T);
     2160
     [93] dp_rest(T);
     (1512)*<<4,0,1>>+(315)*<<4,0,0>>+(-4000)*<<0,0,2>>+(-2800)*<<0,0,1>>
     +(-490)*<<0,0,0>>

