Change log for Magma V2.14-12 (Released 2/5/2008)

Algebraic Curves

·Some bugs have been fixed in the Divisor intrinsics giving the divisor corresponding to a zero-dimensional subscheme of a curve.

Algebraic Function Fields

·The completion mapping for the field defined by y = 0 has been fixed.

·DecompositionType for places of the rational function field has been fixed.

Coding Theory

·AutomorphismGroup for additive codes now returns a more helpful error message when the code is not defined over GF(4). Reported by M. Grassl.

Documentation - Handbook

·A new, corrected version of the Handbook has been compiled.

Elliptic Curves

·A crash in point division has been fixed. Reported by R. Conceicao.

·A bug in the computation of twists of supersingular elliptic curves in characteristics 2 and 3 has been fixed. Reported by J. Cremona.

Galois Groups

·The computation of Galois groups of polynomials over Q(t) (rational function field over the field of rational numbers) has been completely rewritten. As a result, a number of outstanding bugs with wrong results have been fixed, but there is a significant slowdown on some examples. Bugs reported by Kurt Foster and Martin Hintermeier.

·A few minor problems when using invariants over complicated rings has been fixed. Without the fix, certain computations over Q(t) could cause internal errors.

·A bug in the computation of the number of multipliactions in an invariant has been fixed. Without the fix, the function could enter an infinite recursion and terminate Magma.

·A bug in the computation of a bound for the values of the "ProdSum" invariant has been fixed. In certain examples, the wrong bound (too small in general) could have caused wrong results.

Groups

·A bug in finitely presented groups has been fixed. Bug reported by Jack Button.

·A bug in Subgroups function, when restricted to elementary abelian subgroups, has been fixed. Bug reported by Markus Grassl.

·A bug when constructing a sequence of rewrite system groups has been fixed. Bug reported by Jack Schmidt.

·A bug when evaluating an empty sequence of words using Evaluate has been fixed. Bug reported by Henrik Baarnhielm.

·The function CompositionSeries for a permutation group has been upgraded and corrected to give a full composition series for the group, rather than stopping at the soluble residual.

Hyperelliptic Curves

·A bug in the creation of places on hyperelliptic curves has been fixed.

Matrices

·A slow down in matrix multiplication over the rationals has been fixed. Reported by B. Ricard.

Number Fields

·A bug in the computation of conjugates of orders in relative extensions has been fixed. The old code would cause a runtime error.

Orders of Associative Algebras

·Creation of ideals by multiplication of an order and an element has been fixed.

·Equality of orders has been fixed.

·Some bugs in some operations with orders and their elements have been removed.

Real Fields

·BesselFunction has been fixed.