Change log for Magma V2.18-6 (Released 11/5/2012)

Aggregates

·A crash in Xor when one of the sequences is null has been fixed.

·Multiset hashing was returning invalid values for certain underlying types, such as vectors. This has been fixed. Reported by M. Kiermaier.

Arithmetic Geometry

·Changed IsLocallySolvable to not use coproducts when valuations are Infinity(). This works around bugs that were occurring.

Elliptic Curves

·The elliptic curve database of all curves of small conductor has been updated to reflect a recent change of numbering of 98 curves. Requested by J. Cremona.

·MordellWeilShaInformation now additionally uses 8-descent, where necessary.

·An infinite loop occuring occasionally in pAdicEllipticLogarithm (and in IntegralPoints) has been fixed.

·The intrinsic QuarticReduce (used in descent) has been patched to avoid an infinite loop with -6x4 + 12x3 â€“ 7x2 + x.

Extended Reals

·Fixed a possible crash when using extended reals. Reported by M. Kirschmer.

Function Fields

·An internal embedding computation in computing a Galois group of a polynomial over a global rational function field has been corrected.

·A bug has been fixed in OptimizedRepresentation.

Groebner Bases

·An error arising from non-reduced Groebner bases over finite fields of characteristic 2 has been fixed. Reported by M. Stoll.

Groups

·A bug computing the automorphism group of a matrix has been fixed. There were cases where the group found was not the whole automorphism group. Reported by M. Grassl.

·A number of problems when computing the SubgroupLattice of a matrix group have been corrected. Reported by Y. Edel.

Hilbert Modular Forms

·NewSubspace had been accidentally disabled, for spaces of higher weight; it is now available again.

Local Fields

·Fixed a typo in Magma-level printing of extensions of a p-adic field. Reported by T. Dokchitser.

Matrices

·An infinite recursion problem in SmithForm for matrices having very small rank has been fixed. Reported by D. Yasaki.

·A crash involving very large integer matrices has been fixed. Reported by D. Yasaki.

Number Fields

·Fixed a bug with incompatible sequence elements in SplittingField. Reported (and a fix provided) by A. Elkin.

Polytopes

·DatabaseID now returns the database ID of a canonical Fano 3-tope. This requires the most recent version of the canonical3 database (updated 29th March).

·Added PolytopeSmallPolygon for accessing the smallpolygons database. This database lists all polygons, up to translation and change of basis, that fit inside a [0,7] x [0,7] box.

·Points is significantly faster in the case of reflexive polytopes.

·MinkowskiDecomposition and LatticeMinkowskiDecomposition now work for lattice polytopes of arbitrary dimension.

Quadratic Fields

·The preimage of a sequence under a map from a class group into the set of ideals of a maximal order has been fixed.

Ray Class Groups

·RayClassGroup now checks whether its input is a zero ideal. Reported by T. Dokchitser.