Magma V2.21-11 Patch Notes

Commutative Algebra¶

• A crash in Groebner basis computation of algebraic number fields of degree 1 has been fixed.

Elliptic Curve Pairings¶

• A problem with ReducedTatePairing has been fixed. Reported by B. Allombert.

Elliptic Curves¶

• An incorrect answer with Order of a torsion point over a number field has been fixed. The error was that the p-power torsion was not being bounded correctly in some cases. Reported by E. Gonzalez Jimenez.

Function Fields¶

• The application of the Completion mapping and use of Expand have been fixed for non-simple relative extensions.
• UnderlyingRing can now be applied to extensions of infinite degree.
• The CoveringStructure of two sets of places is now a group of divisors which all places in those sets can be coerced into.
• Automorphisms has been fixed for non-simple extensions.
• A crash involving factorization of a chain of function fields (coming from BaseChange for hyperelliptic curves) has been fixed. Reported by M. Stoll.

Groups¶

• An error in applying CayleyGraph to a group of type GrpFP has been fixed. Bug reported by Miles Reid.
• Incorrect printing of certain values in character tables has been fixed. The bug afflicted printing of non-integer values in a cyclotomic field of degree 2, where the magnitude of the coefficients exceeded $2^{30}$. Printing of individual characters and character values was not in error. Bug reported by Eamonn O'Brien.

Lattices¶

• The InnerProductMatrix of a lattice over a real field is now of the correct degree.
• AutomorphismsGroup has been fixed when Bacher polynomials are used.
• ClosestVectors has been fixed in a case where the inner product matrix has large entries.
• BKZ now works for matrices whose rows are dependent. Reported by M. Kudo.

Lie Theory¶

• A crash caused by incorrect input to LieRepresentationDecomposition has been fixed. The crash has become a runtime error. Bug reported by Markus Grassl.

Number Fields¶

• Internal errors with the message "assertion order_basis_real_inv(ord) failed" can no longer occur. (This occurred where a lower bound is obtained on the eigenvalues of a real matrix. Now, appropriate precision is used for this; previously, no attempt was made to do so. This likely meant that the bound obtained was sometimes garbage; it is not known whether this was likely to cause incorrect results to be returned to the user.)
• A major problem (existing for several years) has been fixed, where calls to Completion or LocalRing would corrupt existing local rings. Reported by M.~Stoll.
• A segfault which could occur during calls to various routines has been fixed. Reported by M.~Stoll.
• Significant improvements have been made to conic solving. (As a consequence, descent methods are now effective for certain elliptic curves.)
• The CoveringStructure of two sets of places is now a group of divisors which all places in those sets can be coerced into.
• ChineseRemainderTheorem taking an ideal, a sequence of infinite places, an element and a sequence of signs has been fixed when the element given is in the ideal. Reported by M. Kirschmer.