Change log for Magma V2.22-4 (Released 26/8/2016)

Algebraic Function Fields

·The algorithm choice for computing a 2-element representation of an ideal has been improved. Reported by R. Granger.

Coding Theory

·The function ExtendCode has been restored (accidentally only available as ExtendCodeField previously). Issue reported by D.W.C. Kuijsters.

Commutative Algebra

·A problem with linear factors in reducible polynomials has been fixed. Reported by A-S. Elsenhans.

·Crashes in Groebner basis computation over the rational field has been fixed. Reported by A-S. Elsenhans.

Cubic models of curves

·A crash with PointSearch for cubic models has been fixed.

Dedekind Modules

·A crash involving Dedekind modules has been fixed. Reported by V. Kliuchnikov.

·A crash when constructing a Dedekind module of degree 0 has been fixed. Reported by M. Kirschmer.

Finite Fields

·A crash when trying to compute a logarithm in a large finite field for which the data is not available has been fixed. Reported by M. Tillinghast.

Graphs

·Using 'in' to test whether a set or sequence of vertices is in the edge set of a graph now returns false instead of raising an error when there is no corresponding edge.

Group Characters

·A crash in the group characters code has been fixed. Bug report from Matthieu Rambaud.

·The intrinsic Basis when applied to a character ring now uses the default CharacterTable algorithm, instead of always going to the Dixon-Schneider algorithm.

Groups

·Calls to the ASp functions now trap odd dimensions to give a runtime error. Bug reported by T. Dokchitser.

·A crash when computing projective classical groups over a large finite field has been fixed. Bug reported by T. Dokchitser.

·Incorrect construction of some low dimensional PGO groups fixed. Bug reported by T. Dokchitser.

·Dimension lower bounds on the Spin, SpinPlus and SpinMinus intrinsics are all now 4. This fixes a crash reported by T. Dokchitser.

·The order assigned to PSigmaU(2,q), when q = 3 mod 4, has been corrected. Bug reported by T. Dokchitser.

·An improved access function for a single SmallGroup of order p^7 (p >= 7) is included. Request of E. O'Brien.

Hyperelliptic curves

·A longstanding bug with point counts on genus 1 hyperelliptic curves has been fixed (the twisting parameter was applied twice). Reported by E. Howe.

Lattices

·A crash with BKZ when the number of columns exceeded the rank was fixed. Reported by A.-S. Elsenhans.

Matrix Algebras

·A bug involving the wrong element type when iterating over a matrix lie algebra has been fixed. Reported by J. Maglione.

Numerical Linear Algebra

·A problem with images of complex matrices was fixed.

Sparse Matrices

·A missing error check has been added to Nullspace applied to sparse matrices over rings which are not supported. Reported by D. Yasaki.