---
title: "Magma V2.16-5 Patch Notes"
canonical: "https://docs.magma-maths.org/patchnotes/2.16-5.html"
source: "https://docs.magma-maths.org/patchnotes/2.16-5.md"
---

<a id="magma-v2-16-5-patch-notes"></a>
# Magma V2.16-5 Patch Notes

## Algebraic Geometry

- The computation of affine patches of subschemes of length 1 schemes has been disallowed, consistent with the construction of subschemes of length 0 affine spaces being disallowed.
- A conflict in naming of transcendental generators in functions has been fixed.  Reported by C. Quitte.

## Coding Theory

- A leak in `MinimumWeight` has been fixed.  Reported by M. Grassl.

## Commutative Algebra

- A crash in `Saturation` for zero ideals has been fixed.  Reported by N. Bruin.
- A problem with `ChangeRing` for boolean polynomial rings has been fixed.  Repored by R. Odegard.

## Finite Fields

- A bug in printing of non-reduced finite field elements has been fixed.

## General Local Fields

- Some fixes to the ramified representation maps for degree 1 fields have been made.
- A fix has been made to `FixedField`.

## Groebner Bases

- A crash in `GroebnerBasis(S, d: Faugere := false)` for a sequence of boolean polynomials has been fixed.
- A problem in the final interreduction phase for `GroebnerBasis(S, d)` for a sequence of inhomogeneous polynomials (leading to incorrect results) has been fixed.

## Groups

- A runtime error when computing `Subgroups` of a matrix group over a ring of integers modulo m was incorrect, and has been stopped.

## L-functions

- Some fixes and speedups for symmetric powers particularly with modular forms have been made. based on communications with J. B. Conrey.

## Lists

- One may now obtain a sublist of a list `L` via `L[S]` where `S` is a sequence of indices.

## Matrices

- Problems when computing nullspaces or images of matrices over multivariate rings and fields of fractions have been fixed. Reported by C. Quitte.
- A crash involving huge matrices over algebraic number fields has been fixed.  Reported by S. Humphries.

## Orders of Quaternion Algebras

- A bug in orders of quaternion algebras over rings other than Z has been fixed.
- Some fixes for [`RightIdealClasses`](../Algebras/QuaternionAlgebras/ideal-theory.md#function-rightidealclasses-algquatord) and `Conjugacyclasses` over Q.

## Polynomial Rings

- A slowness in polynomial squaring over finite fields of large characteristic has been fixed.  Reported by Y. Laigle-Chapuy.
- Multivariate polynomial GCD has been sped up in the case that the degree in one variable is much larger than that in the other variables.
- Some very bad inefficiencies in multivariate polynomial powering have been fixed (and a p-adic method is now used for larger exponents). Reported by L. Finotti.
- Problems with loss of precision with polynomial multiplication over inexact rings have been fixed.  Reported by A. Mellit.

## Semigroups and Monoids

- A bug in the coercion of sequences into monoids has bee fixed, the old code would produce internal errors in case of illegal input.

## Sparse Matrices

- A bug involing multiplication of a dense vector by a sparse matrix has been fixed.  Reported by E. Thome.