---
title: "Magma V2.15-9 Patch Notes"
canonical: "https://docs.magma-maths.org/patchnotes/2.15-9.html"
source: "https://docs.magma-maths.org/patchnotes/2.15-9.md"
---

<a id="magma-v2-15-9-patch-notes"></a>
# Magma V2.15-9 Patch Notes

## Function Fields

- A bug with sets of rational function field elements (where the hashing was wrong sometimes) has been fixed. Reported by M. Grassl.

## Groups

- The missing irreducible subgroups of GL(2,2) in the [`IrreducibleMatrixGroup`](../FiniteGroups/DatabasesOfGroups/irrgp-data.md#function-irreduciblematrixgroup-rngintelt-rngintelt-rngintelt) function have been found. Bug reported by C. Roney-Dougal.
- Improved algorithms for computing the soluble radical of matrix groups over the integers and rationals have been included.
- A faster method for computing `ComplementEquationsMatrix` for a module over the rationals has been adopted.
- The functions [`RWSGroup`](../FinitelyPresentedGroups/GroupsDefinedByRewriteSystems/creation.md#function-grprws-rwsgroup) and [`RWSMonoid`](../FinitelyPresentedGroups/GroupsDefinedByRewriteSystems/creation.md#function-rwsmonoid-monfp) have been stopped from leaving an empty file in the /tmp directory at each call. Bug reported by S. Humphries and D. Holt.

## Invariant Rings

- A bug in `FundamentalInvariants` for invariant rings of matrix groups which were not monomial has been fixed. Reported by M. Grassl.
- A crash in [`HomogeneousModuleTestBasis`](../CommutativeAlgebra/PolynomialRingIdealOperations/algebra-module.md#function-homogeneousmoduletestbasis-rngmpol-rngmpol-rngmpol), when given zero polynomials, has been fixed. Reported by M. Grassl.

## Lattices

- A crash when taking an `ActionGenerator` of a G-Lattice has been fixed.

## Modular Symbols

- The empty sequence may now be coerced into the space of modular symbols.

## Polynomial Rings

- A bug in multivariate resultant over finite fields (arising in factorization of polynomials over function fields) has been fixed. Reported by N. Bruin.

## Sparse Matrices

- A bug in [`ModularSolution`](../MatricesLinearAlgebra/SparseMatrices/solution.md#function-smat-modularsolution), which would result in a crash whenever Lanczos was selected without also selecting verbose output, has been fixed. Reported by C. Diem.