Change log for Magma V2.13-6 (Released 3/11/2006)

Algebras

·A proper check on base rings has been inserted in Algebra. Reported by G. Brown.

Coding Theory

·Some crashes in CosetLeaders for fields of size 3, 4, 5, 7, 8 have been fixed.

Geometry

·Multiplication of points on elliptic curves by small integers has been sped up. In particular, computing 2P is now approximately twice as fast.

·Improvement to the calculation of function fields of geometrically reducible (but integral) curves. Reported by F. Hess.

·Improvement to the typing of plane curves.

·Elliptic curves over function fields: 1) Multiple improvements have been made to the TwoSelmerGroup routine (it should now always succeed eventually). 2) A bug has been fixed in LFunction.

Groups

·A bug where the orders of the groups PGammaU and PSigmaU of degree 2 were incorrectly stored has been fixed. This may have shown up in numerous ways e.g. Sylow subgroup computations failing.

·A bug in Subgroups for matrix groups has been fixed. This fixes a crash that occurred when computing the subgroups of a matrix group with non-trivial soluble radical.

·Equality testing and coercion into automorphism groups of groups has been made more general, so that automorphisms with equal, rather than identical, groups as base can be considered to be in the same automorphisms group of the base group. Bug reported by Kasper Andersen.

Invariant Theory

·A bug in ReynoldsOperator for polynomials over the rationals, where the result denominator was wrong, has been fixed. Reported by C. Quitte.

Lie Algebras

·A crash in constructing quotients of Lie matrix algebras has been fixed.

Rings

·A memory leak in Eltseq of local field elements has been fixed.

·ChangePrecision for series rings now handles infinite precision correctly.

·IsPower for series has been fixed.

·Intrinsics requiring PuiseuxExpansions of roots of polynomials over series rings of characteristic p have been improved.

·Factorization of polynomials over series rings has been improved and is now available for polynomials over infinite precision rings.

·Round for polynomials over the reals has been fixed.

·CoefficientRing of an extension of a series field is now the series field rather than the field of fractions of the integers of the series field.

·Some bugs in residue field of ideals of function fields have been fixed. Reported by F. Hess.

·The database of lexicographically minimal irreducible polynomials over GF(2) has been extended to degree 100000.

·Some optional databases of function fields of small degree over small finite fields have been added.