--- title: "Magma V2.27-6 Patch Notes" canonical: "https://docs.magma-maths.org/patchnotes/2.27-6.html" source: "https://docs.magma-maths.org/patchnotes/2.27-6.md" --- # Magma V2.27-6 Patch Notes ## Algebraic Number Fields - A fix has been made to the computation of `GCD`s of elements of quotients of orders. Reported by D. Yasaki. - The default algorithm to compute the class group of number fields does not now use the initial sieving phase by default; to force this on, one should give the parameter `Al := "Sieve"` to functions `ClassGroup`, `ClassNumber`, etc. ## Complex Field - Some bugs in the computation of complex roots of polynomials where the roots were very close to each other have been fixed. Reported by J. Voight and E. Costa. ## Function Fields - The [`GeometricGaloisGroup`](../GlobalFields/AlgebraicFunctionFields/galois.md#function-geometricgaloisgroup-rngupolelt) computation now performs more checks on the values at which the input polynomial is specialised. Reported by D. Krumm. ## Group Algebras - The error message has been made more informative in the case that coercion of a sequence into a group algebra A fails (if the vector representation is not used in A). Issue reported by H. Johnston. ## Group Theory - The maximal subgroups of permutation and matrix groups are now cached after being computed. ## Integer Ring - A message dumped by ECPP has been suppressed. ## Matrices - Matrix multiplication over a class of finite fields [`GF(p^e)`](../BasicRings/FiniteFields/creation.md#function-gf-rngintelt) where $p>7$, $e$ is composite and $p^e > 2^{20}$ has been improved (including parallelisation). Issue reported by C. Rito. - Matrix multiplication over [`GF(p)`](../BasicRings/FiniteFields/creation.md#function-gf-rngintelt) for medium-sized $p$ has been improved in the AVX2 executable. - A bug in the algorithm for computing the Hermite Normal Form of a certain type of sparse integer matrix has been fixed. Reported by H. Johnston. ## Modular Curves - Fixed a possible crash in `ModularDegree` that was introduced in V2.26-6. ## Multivariate Polynomials - The input type to `NewtonPolygon` has been generalised to `RngMPolEltGL`. - The input type to [`CoefficientNumerator`](../BasicRings/MultivariatePolynomialRings/operation-element.md#function-coefficientnumerator-rngmpolelt) and [`CoefficientDenominator`](../BasicRings/MultivariatePolynomialRings/operation-element.md#function-coefficientdenominator-rngmpolelt) has been generalised to `GenMPolBElt`. ## Rational Field - New function [`HJContinuedFraction(r)`](../BasicRings/Rationals/element.md#function-hjcontinuedfraction-fldratelt) which takes a rational $x$ and returns the sequence of partial quotients of the Hirzebruch-Jung continued fraction expansion of $x$. Related new function [`HJContinuedFractionValue(C)`](../BasicRings/Rationals/element.md#function-hjcontinuedfractionvalue-rngintelt) which takes such an expansion and returns the corresponding rational number. ## Schemes - A crash in `Dimension` for schemes over non-fields has been fixed. Reported by N. Katz.