---
title: "Magma V2.13-15 Patch Notes"
canonical: "https://docs.magma-maths.org/patchnotes/2.13-15.html"
source: "https://docs.magma-maths.org/patchnotes/2.13-15.md"
---

<a id="magma-v2-13-15-patch-notes"></a>
# Magma V2.13-15 Patch Notes

## Elliptic Curves

- The identity point on an elliptic curve over a p-adic field behaves somewhat better now. In particular, it is possible to coerce the coordinates of the identity point back into the curve.
- [`IsogenyFromKernelFactored`](../ArithmeticGeometry/EllipticCurves/morphism.md#function-isogenyfromkernelfactored-schgrpell) applied to a group scheme now works (formerly triggered a runtime error).
- Fixed a bug in [`IsogenyFromKernel`](../ArithmeticGeometry/EllipticCurves/morphism.md#function-isogenyfromkernel-schgrpell) that would cause the resulting isogeny to be incorrect when the kernel contained the full two-torsion and the base field was not the rationals or a small finite field.

## Hyperelliptic curves

- The map `phi` returned by `TwoSelmerGroup` was completely wrong in some cases, and has been corrected. (This problem was introduced in V2.13.) Reported by Patrick Corn.

## Invariant Theory

- A bug in `Module`, when the secondaries were set via the attribute, has been fixed. Reported by D. Wehlau.

## Lattices

- Problems lattice vector enumeration has been fixed (when the bound was close to the machine int size). Problem reported by Ronald van Luijk.
- A problem with the construction of sub-lattices of lattices with real valued gram matrices has been fixed. Without this, Magma would encounter internal errors.

## Models of genus one curves

- A mistake in the `HyperellipticCurve` constructor has been corrected. Prior to this, for a model $f(X)$ of degree $2$ without cross-terms, `HyperellipticCurve` returned $y^2 = -f(x)$ instead of $y^2 = f(x)$. Reported by Bjorn Poonen.

## Modules over Dedekind domains

- A bug in the handling and printing of parents of pseudo-matrices has been fixed. Without this fix, a sequence of pseudo matrices could cause internal errors. Bug reported by U. Staemmler.

## Number Fields

- Several minor problems in the class group computation of number fields have been fixes. Together, they would trigger internal errors. Reported by N. Bruin.
- A bug in the unit group computation that, especially in fields with unit rank $\ge 5$ and small regulator could result in infinite loops, has been fixed. Bug reported by M. Kirschmer.

## Polynomial Rings

- A bug in factorization of polynomials over function fields over quotient rings has been fixed. Reported by N. Bruin.

## System

- Some bugs relating to interactions between integer factorization sequences (`RngIntEltFact`) and normal sequences (`SeqEnum`) have been fixed.