Magma V2.28-26 Patch Notes

Algebraic Number Fields¶

• A crash has been fixed in the computation of UnitGroups.
• A crash in ext<> for number fields when given a sequence of integers has been fixed. Reported by Lewis Combes.

Elliptic Curves¶

• The functions WeilPairing(P, Q, n) and TatePairing(P, Q, n) now first attempt to coerce Q into the parent of P if these parents are not identical. Issue reported by Sachi Hashimoto.

Hyperelliptic Curves¶

• The function HeightConstant now sometimes gives a better bound for the difference between naive and canonical height on Jacobians of genus 2 curves, for instance in Example 6.2 of the recent paper of Garcia-Fritz and Pasten. Improved code supplied by Steffen Mueller and Michael Stoll.

Integers¶

• Fixed a bug with ShiftRight that would return an answer one too low if a negative number was shifted and the result should have been exact.

Language¶

• A crash in assignment (in a certain situation involving multiple RHS values) has been fixed. Reported by Antoine Joux.

Lattices¶

• A crash in ClosestVector involving a lattice with very large entries in its basis matrix has been fixed. Reported by Markus Kirschmer.
• A crash in HKZ with the Unique parameter and a transformation matrix matrix has been fixed. Reported by Hao Guo.

Matrices¶

• A bad slowdown when computing the Smith Normal Form with transformation matrices for a sparse matrix defined over a ring which is not the integer ring has been fixed.

Matrix Groups¶

• An incorrect result for CompositionTreeCompositionFactors applied to the Lyons group has been fixed. Reported by David Craven.
• A new optional parameter Sign has been added to DoubleCoverSymmetricGroup which is the opposite of the existing Type. Added by Derek Holt after discussion with David Craven.

Polynomial Rings¶

• A crash in Discriminant (arising from IsEasySnAn) for very large integer polynomials has been fixed. The algorithm has been sped up at the same time. Reported by Nick Katz.