Change log for Magma V2.24-9 (Released 31/7/2019)

Algebras

·A problem with the map returned by VectorSpace for subalgebras of group algebras has been fixed. Reported by S. Humphries.

Conics

·An occasional problem with an uninitalized array with Lagrange's method over number fields has been fixed.

Elliptic Curves

·The FaltingsHeight in the case of curves with non-integral j-invariant has been corrected. It now agrees with FaltingsHeight2 though neither is normalized as per Deligne. Also, the Handbook gives an incorrect formula this. Reported by A. Kresch.

Fuchsian Groups

·A problem with parameters in FuchsianGroup has been fixed.

Galois Groups

·Primes specified by the parameter Prime to GaloisGroup are now checked for being unramified. Reported by J. Voight.

·Some extra printing has been removed from GaloisGroup computations for reducible polynomials. Reported by D. Krumm.

·HilbertIrreducibilityCurves will now return curves whose defining polynomials use the print names of the Parent of the input polynomial. Reported by D. Krumm.

Graph Theory

·Tuples of the form  are now properly handled by the network constructor. Reported by W. Bosma.

Groups

·A bug in the computation of the Frattini subgroup of a matrix group has been fixed. When the matrix group was a p-group, a proper subgroup of the Frattini subgroup may have been returned. Bug reported by Martin van Beek.

·The representation of ATLAS group 2J2d2 contained in GL(448, 7) has been corrected. Bug reported by E. O'Brien.

Hyperelliptic Curves

·A bug was fixed in the Selmer machinery, which occasionally caused wrong results for RankBounds to be returned. A preconditioning attempt to use a better model in MonicModel was accidentally replacing the curve by a nonisomorphic one. Reported by J. Doyle.

Lattice over Number Fields

·A problem with Sphere was fixed. Reported by M. Kirschmer.

Modules

·A bug in IsSurjective for Hom-modules has been fixed. Reported by D. Craven.

Number Fields

·Factorization of polynomials over orders of number fields or their field of fractions has been fixed for large degree orders.

·Setting up of coercions between fields in CompositeFields has been improved to reduce failures of applying these coercions. Reported by J. Voight.

·The computation of Valuations when the ideals are of an order not known to be maximal has been improved. Reported by L. Liu.

·A crash with the number field sieve (quadratic case) has been fixed, involving multiple divisors of the discriminant in the range around 1000 causing a buffer overflow. Example: 218467444968689005796305.

Polynomial Rings and Groebner Bases

·The function Degree has been fixed to return -1 when a grading is present and the input polynomial is zero. Reported by M. Zieve.

·Some bugs in local polynomial rings have been fixed. Coordinates(I, f) in the local polynomial situation now returns C and d so that &+[C[i]*B[i]: i in .. #B] eq d*f where B := Basis(I). Problems reported by G. Blanco.

Series Rings

·Constructing a homomophism from an extension of a series ring previously did not allow a coefficient homomorphism to be provided. This is now allowed. Reported by J. KlÃ¼ners.

Sparse Matrices

·A crash in Rank for sparse matrices over GF(2) has been fixed. Reported by S. Goldstein.

System

·Following a bug report by S. Humphries, a memory management problem has been fixed. This was to do with the ^^ constructor.