Magma V2.29-3 Patch Notes

Aggregates¶

• For associative array $A$ with a default value assigned, IsDefined(A, x) has been fixed to return true when a value for $x$ has not been explicitly assigned, while IsInKeys(A, x) returns whether a value for $x$ has been explicitly assigned. In both cases, if the result is true, the second return value is the value $A[x]$.

Algebraic Curves¶

• Error checking for compatibility of differentials has been added. Reported by Jeremy Booher.

Algebraic Number Fields and Orders¶

• Compositum involving fields with known embeddings has been fixed. Reported by Abhijit Mudigonda.
• New function PrimeRepresentative computes a prime ideal in a given ideal class.

Coding Theory¶

• The parameter Nthreads is now handled properly if the dual code is used in the function WeightDistribution. Reported by Markus Grassl.

Congruence Subgroups of PSL_2(R)¶

• A bug in IsEquivalent, a function testing equivalence of points in the upper half plane by a congruence subgroup, has been fixed.

Elliptic Curves¶

• Functionality of elliptic curves over $p$-adic fields has been improved, especially using IsogenyFromKernel. Reported by Sachi Hashimoto.
• The map returned by DualIsogeny is now an isogeny rather than an arbitrary map of schemes. Reported by Ignasi Sánchez Rodríguez.

Galois Groups¶

• Support for ramified p-adic splitting fields for Galois groups over the rationals has been added.

Groups¶

• A bug where the Subgroups is given an order or index filter which doesn't divide the group order produced too many (ie any) subgroups has been fixed. Bug reported by Tendai Shumba.
• A problem when computing automorphisms of p-groups has been addressed. Reported by Eamonn O'Brien.

Hyperelliptic Curves¶

• Functionality involving computation of local data has been improved. Reported by Ariel Pacetti.
• A crash in MordellWeilGroupGenus2 (arising from inconsistent abelian group hom preimages) has been fixed. Reported by Drew Sutherland and Michael Stoll.

Integer Ring¶

• TrialDivision(n, B) has been sped up for the case that $B>2^{30}$.
• A failure in the MPQS algorithm for relatively small integers has been fixed.

Language¶

• A crash when calling a procedure with no name at the top level has been fixed.
• Option -V (or --version) has been added so that Magma prints the version immediately and then exits immediately. Suggested by H{\aa}vard Damm-Johnsen.

Lattices¶

• A crash in ClosestVectors with large real entries have been fixed. Reported by Stefano Marseglia.
• Some problems in short vector enumeration for lattices with very large bases have fixed (including print messages when the minimum was incorrectly adjusted). Reported by David Zuerick-Brown.
• JordanDecomposition(L, p) for $L$ of type LatNF has been fixed so that the type of the returned matrices is AlgMatElt.
• A failed assert in Dual where the lattice has no ambient inner product matrix has been fixed. Reported by Stefano Marseglia.

Local Fields¶

• The map returned as the third return value from GaloisGroup of a local field now returns a map rather than a function when given input of the identity element of the group, consistent with maps being returned when the input is a non identity element. Reported by Kevin Keating.
• Allow coercion between unramified extensions when coercion is available between their residue class fields. Reported by Sachi Hashimoto.

Modular forms over imaginary quadratic fields¶

• Type mismatch between documentation and intrinsic in Eigenform has been fixed. Reported by H{\aa}vard Damm-Johnsen.