--- title: "Magma V2.19-7 Patch Notes" canonical: "https://docs.magma-maths.org/patchnotes/2.19-7.html" source: "https://docs.magma-maths.org/patchnotes/2.19-7.md" --- # Magma V2.19-7 Patch Notes ## Algebraic Function Fields - Factorization of polynomials over some representations of function fields has been fixed. - When a non-simple extension is constructed it is now checked that the resulting extension will be separable and if not an error occurs. ## Algebraic Number Fields - Memory handling has been fixed when constructing a quotient of an order by an existing ideal. ## Algebraic Surfaces - The parametrization routine for degree 9 Del Pezzo surfaces over the rationals [`ParametrizeDegree9DelPezzo`](../AlgebraicGeometry/AlgebraicSurfaces/dp-srfcs.md#function-parametrizedegree9delpezzo-sch) has been speeded up by use of additional basis normalisations and an alternative algebra trivialisation algorithm. It also now returns an isomorphism with inverse map data included. `ParametrizeDelPezzoDeg9` is now simply a synonym for this main intrinsic. ## Arithmetic Geometry - A bug in [`qCoverDescent`](../ArithmeticGeometry/HyperellipticCurves/cyclic-covers.md#function-qcoverdescent-rngupolelt-rngintelt) reported by N. Freitas has been fixed. ## Commutative Algebra - A problem when coercing between function fields (affecting `PrimaryDecomposition`) has been fixed. Reported by D. Kohel. - A crash in `SyzygyModule` has been fixed. Reported by M. Reid. ## Elliptic Curves - A bug in `TorsionBound` for elliptic curves over a number field has been fixed. ## Finite Geometry - A crash that could arise when computing automorphisms of planes has been fixed. Reported by J. Key. - Magma-level printing of planes now uses the correct constructor name. ## Graph Theory - The version of `nauty` included within Magma has been upgraded to 2.5r2. ## Groups - A crash when computing the socle of a permutation group has been fixed. - A crash computing `AbelianQuotient` of an fp-group has been fixed. Bug reported by Derek Holt. - A crash, and some issues with the algorithm, when computing `Centre` of a pc-group have been fixed. Crash reported by Stephen Humphries. - A bug in `IsIrreducible` applied to a group character constructed by `Induction` has been fixed. Bug reported by Derek Holt. - A bug where the `PolycyclicGroup` constructor failed to detect an uncollected word appearing as the RHS of a relation has been fixed. Such a relation will now give a runtime error. Reported by E. O’Brien. - A small collection of problems that can arise when computing the socle of a primitive permutation group having degree in the range $10^6$ to $10^7$ has been fixed. - A crash due to the incorrect construction of the order of the matrix group [`GOPlus`](../FiniteGroups/AlmostSimpleGroups/standard.md#function-goplus-rngintelt-rngintelt)`(2,4)` has been fixed. Bug reported by U. Thiel. ## L-functions - A bug with computing the Hodge structure of a tensor product was fixed. Reported by D. Roberts. ## Polynomial Rings - The variable parameters to [`SmallRoots`](../BasicRings/UnivariatePolynomialRings/operation-element.md#function-smallroots-rngupolelt-rngelt-rngelt) have been changed to allow more specific types than just `RngElt`. - A bad slowness in exact division of multivariate polynomials has been fixed. Reported by M. Grassl. ## Polytopes and Polyhedra - The new intrinsic [`EdgeFacetIncidenceMatrix`](../Geometry/Polytopes/cones-polyhedra.md#function-edgefacetincidencematrix-torpol) can be used to calculate the edge-facet incidence matrix of a polyhedron. - The new intrinsic [`NormalEdgeCones`](../Geometry/Polytopes/basic-combinatorics.md#function-normaledgecones-torpol) can be used to recover the (outer) normal cones of the edges of a polyhedron. When working with polytopes, this is significantly faster than the equivalent sequence of calls to [`NormalCone`](../Geometry/Polytopes/basic-combinatorics.md#function-normalcone-torpol-torpol). ## Quadratic Forms - A bug in [`QuadraticClassGroupTwoPart`](../GlobalFields/QuadraticFields/structure_ops.md#function-quadraticclassgrouptwopart-fldquad) for integers with large even 2-valuation and an odd number prime factors 3 mod 4 was fixed. Reported by J. Stankewicz. ## Schemes - There are new intrinsics for Segre embedding - [`SegreEmbedding`](../AlgebraicGeometry/Schemes/schemes-ambient.md#function-segreembedding-sch) and [`SegreProduct`](../AlgebraicGeometry/Schemes/schemes-ambient.md#function-segreproduct-seqenum-sch) - and for blowing up points or subschemes: `BlowUp`. These have already been documented in the online version of the Handbook. - The [`RemoveLinearRelations`](../AlgebraicGeometry/Schemes/schemes-creation.md#function-removelinearrelations-sch) intrinsic now copies across attributes from the original scheme to the scheme that is returned. ## Sparse Matrices - The dense back end of the sparse Smith algorithm has been improved. Problem reported by E. O’Brien. ## System - Creating a real field with 52 bits of precision no longer produces a copy of the parent of timings. - A problem with indicating the wrong source line on bad sequence indexing has been fixed. Reported by S. Humphries.