Change log for Magma V2.17-5 (Released 18/2/2011)

Coding Theory

·A bug that could cause crashes when creating a quantum code with the ExtendedFormat parameter set has been fixed. Reported by M. Grassl.

Groups

·A bug in permutation group base and strong generating sets has been fixed. The bug was noticed as a crash while computing Galois groups of degree 170+ polynomials over the rationals.

·The function FactoredClassicalGroupOrder has been added at the request of E. O'Brien.

·A crash in PermutationRepresentation of an automorphism group has been fixed. Bug reportd by D. Howden.

·A crash caused by giving the Evaluate command a null sequence of images has been trapped to give a runtime error. Bug reportd by D. Howden.

·An occasional crash when reading transitive groups from the database has been fixed.

·The speed of access when reading transitive groups from the database has been improved.

Hyperelliptic Curves

·The LSeries of a hyperelliptic curve now first transforms the curve into a MinimalWeierstrassModel (rather than a ReducedModel). This will give solve some problems at p=2, though others still remain.

·A bug with an identification of "hyperelliptic" curves of genus < 2 has been fixed.

Local Fields

·A signature PrincipalUnitGroupGenerators for RngPadRes has been added which fixes UnitGroupGenerators for RngPadRes.

·A coercion into an extension field from a base field has been improved avoiding a low precision intermediate calculation. Reported by Tim Dokchitser.

Number Fields

·A failed inversion in a quotient of some order would cause some printing on the screen. Reported by M. Kirschmer.

·Computations of class groups and class numbers of number fields defined by pure polynomials could result in internal errors.

·Some computations of MaximalOrders of Kummer extensions have been fixed. This fix applies to function fields which are Kummer extensions also. Reported by E. ThÃ³me.

Polynomial Rings

·A slowdown in bivariate factorization in characteristic 2 has been fixed.

Primality Proving

·A bug for 96-bit inputs to ECPP on 32-bit computers has been fixed.

Special Functions

·The signature for JBessel has been restricted to require that the first argument is integral. This is the only implemented case in any event.

Symmetric Function Algebras

·Coercion of a (multivariate) polynomial into a symmetric function algebra over its polynomial ring now works. Reported by A. Kasprzyk.