Magma V2.18-6 Patch Notes

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 $-6x^4 + 12x^3 - 7x^2 + x$.

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.