Change log for Magma V2.19-10 (Released 18/10/2013)

Algebraic Curves

·Added proper error messaging for some cases in the suite of gonal maps functionality - in particular, in Genus6GonalMap - where there is a failure in small characteristics because of implementational problems in explicitly splitting a Lie Algebra. Reported by S. Kochinke for an example in characteristic 3.

Algebraic Function Fields

·Elements are now constructed with respect to an equation order basis, as this is considerably more efficient for arithmetic.

·A crash has been fixed in forming the sum of two orders (in the case where one summand is an equation order).

·A fix has been made in GaloisGroup for polynomials over function fields.

·LPolynomial and ZetaFunction are now available for function fields with larger genus or constant fields than before. Reported by Liu Xiaogang.

Algebraic Number Fields

·A problem has been fixed which caused AbsoluteAlgebra to fail to terminate. Reported by N. Freitas.

·A problem in ClassGroup has been fixed; it failed to terminate for a certain (easy) example. Reported by D. Smertnig.

·A fix has been made in GaloisGroup, in the case of non-monic reducible polynomials.

·A crash has been fixed in forming the sum of two orders (in the case where one summand is an equation order).

·A crash in some SolveByRadicals computations has been fixed.

·A crash has been fixed in AbsoluteField in the case of a linear extension by a non-integral polynomial.

·A memory leak has been fixed in IsSquare for elements of number fields. Reported by L. DembÃ©lÃ©.

Basic Algebras

·Some bugs have been fixed and some methods have been improved. Code supplied by J.F. Carlson.

Commutative Algebra

·A simple problem with meet for affine algebras has been fixed. Reported by C. Quitte.

·Rational function fields over fields of fractions of affine algebras are now supported properly.

Elliptic Curves

·A bug has been fixed in the elliptic curve Chabauty routine, where it returned with too small a set of points. Reported by N. Freitas and M. Stoll.

Groups

·A crash when constructing subgroups of a finitely presented group has been fixed. This crash was found by an unknown user of the online calculator.

·A memory leak in the Subgroups class of functions for matrix and permutation groups has been fixed.

Lattices

·A crash when computing the automorphism group of a lattice has been fixed. The bug was due to the ShortestVectorsMatrix of the lattice being possibly incorrect when it is very large. This problem has been fixed. Bug reported by G. Nebe.

Modular Curves

·The CuspPlaces intrinsic in the small modular curves package now returns a sequence in all cases. Reported by S. Siksek.

Modules over Dedekind Domains

·A fix has been made to the construction of a module from a sequence of ModRng elements.

Polynomial Rings

·Coercion into a quotient polynomial ring has been fixed so that elements from recursive base rings are handled properly. Reported by N. Bruin.

Series Rings

·The handling of zero roots of polynomials over series rings has been improved, sometimes zero roots were listed twice.

·A crash has been fixed in HasRoot for polynomials over series rings when a root could not be computed.