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Patch Notes

Magma V2.21-5 Patch Notes

Patch release for Magma V2.21-5. Updated areas: Algebraic Number Fields, Commutative Algebra, Dirichlet Characters, Elliptic Curves, Groups and 2 more.

7 areas

Algebraic Number Fields

  • An iterator has been provided to iterate through elements of quotients of orders of relative number fields by their ideals. Reported by M. Kirschmer.
  • It is now possible to construct Random elements of quotients of orders of relative number fields by their ideals.
  • Compatibility has been improved for orders of number fields. This allows the comparison of orders having the same coefficient ring using eq. Reported by M. Kirschmer.

Commutative Algebra

  • A problem in comparison of module elements has been fixed. Reported by C. Quitte.

Dirichlet Characters

  • A problem with assigning names to a Dirichlet group generators was fixed.

Elliptic Curves

  • The MinimalQuadraticTwist intrinsic when applied to a rational whose numerator has a prime-power divisor $p^e$ with $6|e$ and $p>3$ congruent to 3 mod 4 could return a curve with a different $j$-invariant. Reported by A. Sutherland.

Groups

  • A bug in Subgroups when using IndexEqual set to an impossible index has been fixed. Reported by A. Sutherland.
  • A crash using the transversal map with groups of type GrpFPCox has been fixed. Reported by B. Howlett.
  • If explicitly setting all of the conjugacy classes of a group, they are no longer re-ordered if they are already sorted. Previously, elements with the same order and length could be re-ordered in this case. Reported by S. Goldstein.
  • A crash when computing preimages with a BlocksAction map has been fixed. Bug reported by Juergen Klueners.

Lattices

  • Using the Max parameter with ShortestVectors could lead to incorrect caching of partial information, and give erroneous results for later enumerations. Reported by C. Doberstein.

Series Rings

  • The IsSquare intrinsic for series over the rationals whose constant coefficient (after removing the valuation) was not 1 could give wrong answers due to Log/Exp not working. The same problem can also occur with IsPower more generally. Reported by M. Stoll.
  • Roots, to a given precision, of polynomials over series rings over inexact rings have been disallowed.
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