Change log for Magma V2.27-4 (Released 29/8/2022)

Abelian Fields

·A bug in computing the ArtinMap of an abelian extension constructed from a map from the trivial group has been fixed. Reported by C. Schembri.

Elliptic Curves

·A hang in TwoSelmerGroup for elliptic curves with very large coefficients has been fixed. Reported by M. Voznyy.

Finite Fields

·Arithmetic has been sped up for computations in the fields GF(p2) for large p.

·IrreduciblePolynomial(GF(p), n) has been fixed to return a binomial polynomial always for large p when possible; certain cases had been missed previously.

Groebner Bases

·A slowdown in the F4 algorithm for certain types of ideals has been fixed. Reported by M. Grassl.

·A hang in Groebner basis computation over the rational field for a certain type of input has been fixed. Reported by T. Fisher.

Groups

·A missing check that N is normal in G for the call Subgroups(G, N) has been fixed. Reported by E. Rains.

Linear Programming

·A crash in the linear programming code (coming from a call to RegularSequence) has been fixed. Reported by I. Ilmer.

Matrices

·A bug when computing random matrices over the finite field GF(2^32) has been fixed. Reported by E. O'Brien.

·The computation of the nullspace of sparse matrices over the rational field has been sped up for certain types of input. This speeds up some types of computation with modular forms.

·A hang in matrix inverse over cyclotomic fields for non-invertible matrices has been fixed. Reported by E. Rains.

Number Fields

·A crash in the computation of the absolute field of a number field with very large coefficients has been fixed (arising when calling DescentInformation on certain types of elliptic curves). Reported by M. Voznyy.

Polytopes

·An issue where NumberOfInteriorPoints could be off by one for one-dimensional rational polytopes has been fixed. Reported by G. Hamm and J. Hofscheier, who also provided the fix.

Schemes

·An internal crash in BaseScheme called out of Extend for schemes has been fixed. Reported by T. Keller.

·The parameter SkipSingularityCheck has been added to the function RationalPoints so that the singularities check can be skipped at the beginning so that the function does not fail on singular inputs. Example input reported by D. Brown.

p-adic Rings and their Extensions

·A SeriesPrinting attribute has been added to the p-adic rings and fields and their extensions. When this attribute has been set to true for a ring or field, elements of that ring or field will be printed as a series in the uniformizing element.