Change log for Magma V2.21-3 (Released 30/3/2015)

Commutative Algebra

·An bug in IsPrime for positive-dimensional ideals over finite fields of medium characteristic has been fixed. Reported by N. Bruin.

Dirichlet and Hecke Characters

·The creation intrinsics DirichletCharacter and HeckeCharacter can now take a list as an argument instead of a tuple.

·The intrinsic GrossenTwist has been expanded to include twists by Hecke characters of the same modulus, and also returns a kernel corresponding to characters that are trivial on the given data.

Elliptic Curves

·A crash with large degrees in FrobeniusMap is now avoided.

·A problem with computing Euler factors at good primes (over a number field) which divide the denominator of the a-invariants has been fixed. Reported by F. Brunault.

Groups

·A crash in IsCyclic when applied to the trivial matrix group has been fixed. Bug reported by Andrew Sutherland.

·A crash to do with HomomorphismsProcess, when no homomorphisms are found, has been fixed. Bug reported by Jan Karabas.

Number Fields

·The meet of 2 number fields which are defined as extensions of different coefficient fields has been fixed.

Polynomials

·A problem with multiplication of polynomials whose trailing terms were inexact elements of an exact ring, for instance a constant coefficient O(t^4) in a power series ring of fixed precision 20 over GF(3), has been fixed. Reported by B. Allombert in the context of factorization of polynomials over Laurent series rings.

·A crash when taking GCD of polynomials over a GaloisRing has now been disallowed.

·A crash in factorization of multivariate polynomials over a number field with a non-monic defining polynomial has been fixed.

Sparse Matrices

·A missing error check in Echelonize has been inserted. Reported by R. Zeier.

Symmetric Function Algebras

·Taking the characteristic of a symmetric function algebra no longer crashes.

·Polynomial arithmetic over symmetric function algebras no longer crashes. Reported by A. Duncan.

System

·The description of GetDefaultRealField now has the correct return type.

·The deprecated FldPr and FldPrElt types have been removed. Note: As a consequence, workspaces saved before this patch release will not be able to be properly restored by it.