Add a zero_vector(TpM), update News.md and add a GH Action for the Ne…

…ws.md

.github/workflows/changelog.yml

@@ -0,0 +1,12 @@
+name: Check Changelog
+on:
+  pull_request:
+
+jobs:
+  Check-Changelog:
+    name: Check Changelog Action
+    runs-on: ubuntu-latest
+    steps:
+      - uses: tarides/changelog-check-action@v2
+        with:
+          changelog: NEWS.md

NEWS.md

@@ -5,7 +5,19 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [0.15.0] dd/mm/2023
+## [0.15.1] 30/10/2023
+
+### Added
+
+- `zero_vector(TpM)` to generate a zero vector in the tangent space
+- a GitHub CI action that errors, when this file was not updated on a PR
+
+### Fixed
+
+- `is_point` and `is_vector` for the tangent space now correctly forward to
+  vector checks on the corresponding manifold. The same for both `check_size`s
+
+## [0.15.0] 21/10/2023
 
 ### Added
 

src/TangentSpace.jl

@@ -257,11 +257,20 @@ Weingarten(::TangentSpace, ::Any, ::Any, ::Any)
 
 Weingarten!(::TangentSpace, W, X, V, A) = fill!(W, 0)
 
+@doc raw"""
+    zero_vector(TpM::TangentSpace)
+
+Zero tangent vector in the [`TangentSpace`](@ref) `TpM`,
+that is the zero tangent vector at point `TpM.point`.
+"""
+zero_vector(TpM::TangentSpace) = zero_vector(TpM.manifold, TpM.point)
+
 @doc raw"""
     zero_vector(TpM::TangentSpace, X)
 
 Zero tangent vector at point `X` from the [`TangentSpace`](@ref) `TpM`,
-that is the zero tangent vector at point `TpM.point`.
+that is the zero tangent vector at point `TpM.point`,
+since we identify the tangent space ``T_X(T_p\mathcal M)`` with ``T_p\mathcal M``.
 """
 zero_vector(::TangentSpace, ::Any...)
 

test/test_sphere.jl

@@ -54,5 +54,6 @@ include("test_manifolds.jl")
         @test !is_point(TpM, p)
         @test is_vector(TpM, X, X)
         @test !is_vector(TpM, X, p)
+        @test zero_vector(TpM) == zero_vector(M, p)
     end
 end