Hello!

While computing some Gcds in LaurentPolynomialRing(Rationals) I
noticed that Gcd(0*q,0*q) (where q=Indeterminate(Rationals) causes an
error. The reason is that
FieldLaurentPolynomialRingOps.StandardAssociate doesn't work for the 0
polynomial.

I therefore suggest the following changes to gap/lib/polyfld.g
(analogous to PolynomialRingOps.StandardAssociate):

*** polyfld.g   Tue Nov 09 00:54:00 1993
--- ../polyfld.g        Sun Apr 17 17:53:12 1994
***************
*** 53,59 ****
  #F  FieldPolynomialRingOps.StandardAssociate( <R>, <f> )  . . . .  normed pol
  ##
  FieldPolynomialRingOps.StandardAssociate := function( R, f )
!     return f * f.coefficients[ Length( f.coefficients ) ]^-1;
  end;


--- 53,63 ----
  #F  FieldPolynomialRingOps.StandardAssociate( <R>, <f> )  . . . .  normed pol
  ##
  FieldPolynomialRingOps.StandardAssociate := function( R, f )
!     if 0 < Length( f.coefficients ) then
!         return f * f.coefficients[ Length( f.coefficients ) ]^-1;
!     else
!         return f;
!     fi;
  end;


***************
*** 228,236 ****
  ##
  FieldLaurentPolynomialRingOps.StandardAssociate := function( R, f )
      local   l;
!
!     l := f.coefficients[Length(f.coefficients)];
!     return Polynomial( R.baseRing, f.coefficients*l^-1 );
  end;


--- 232,244 ----
  ##
  FieldLaurentPolynomialRingOps.StandardAssociate := function( R, f )
      local   l;
!
!     if 0 < Length( f.coefficients ) then
!         l := f.coefficients[Length(f.coefficients)];
!         return Polynomial( R.baseRing, f.coefficients*l^-1 );
!     else
!         return f;
!     fi;
  end;

--
Harald Boegeholz | hwb@mathematik.uni-stuttgart.de
| os2a@info2.rus.uni-stuttgart.de