Fix identity_element on TranslationGroup with StaticArrays types (#35)

* Fix identity_element on TranslationGroup with StaticArrays types
* fix test
* fix

---------

Co-authored-by: Ronny Bergmann <[email protected]>

Author: mateuszbaran

NEWS.md

@@ -5,12 +5,20 @@ All notable Changes to the Julia package `LieGroups.jl` will be documented in th
 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).
 
-## [0.1.1] unreleased
+## [0.1.1] 2025-05-05
+
+### Added
+
+* `identity_element` on `TranslationGroup` supports now `StaticArrays.jl` types.
 
 ### Changed
 
 * the tutorials are now rendered with `quarto` using the [`QuartoNotebookRunner.jl`](https://github.com/PumasAI/QuartoNotebookRunner.jl) and are hence purely julia based.
 
+### Fixed
+
+* `identity_element` on `TranslationGroup` no longer accepts a number as a second argument (it accepts number type instead).
+
 ## [0.1.0] 2025-04-22
 
 Everything denoted by “formerly” refers to the previous name in [`Manifolds.jl`](https://juliamanifolds.github.io/Manifolds.jl/stable/).

Project.toml

@@ -1,7 +1,7 @@
 name = "LieGroups"
 uuid = "6774de46-80ba-43f8-ba42-e41071ccfc5f"
 authors = ["Seth Axen <[email protected]>", "Mateusz Baran <[email protected]>", "Ronny Bergmann <[email protected]>", "Yueh-Hua Tu", "Olivier Verdier <[email protected]>"]
-version = "0.1.0"
+version = "0.1.1"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

src/group_operations/addition_operation.jl

@@ -140,16 +140,18 @@ identity_element(::LieGroup{𝔽,AdditionGroupOperation}) where {𝔽}
 
 function identity_element(
     ::LieGroup{𝔽,AdditionGroupOperation}, ::Type{T}
-) where {𝔽,T<:Union{Number,AbstractArray{0,<:Number}}}
+) where {𝔽,T<:Union{Number,AbstractArray{<:Number,0}}}
     return zero(T)
 end
 function identity_element(
     ::LieGroup{𝔽,AdditionGroupOperation}, ::Type{Array{T,0}}
 ) where {𝔽,T<:Number}
     return fill(zero(T))
 end
-function identity_element(::LieGroup{𝔽,AdditionGroupOperation}, e::Number) where {𝔽}
-    return zero(e)
+function identity_element(
+    ::LieGroup{𝔽,AdditionGroupOperation}, T::Type{<:StaticArray}
+) where {𝔽}
+    return zero(T)
 end
 
 @doc "$(_doc_identity_element_add)"

test/groups/test_translation_group.jl

@@ -1,4 +1,4 @@
-using LieGroups, Random, Test
+using LieGroups, Random, Test, StaticArrays
 
 s = joinpath(@__DIR__, "..", "LieGroupsTestSuite.jl")
 !(s in LOAD_PATH) && (push!(LOAD_PATH, s))
@@ -69,4 +69,9 @@ begin
             test_group_action(A, properties2, expectations2)
         end
     end
+
+    @testset "StaticArrays" begin
+        @test identity_element(G, SVector{3,Float64}) === zero(SVector{3,Float64})
+        @test identity_element(G, MVector{3,Float64}) == zero(MVector{3,Float64})
+    end
 end

test/operations/test_addition_operation.jl

@@ -4,6 +4,8 @@ s = joinpath(@__DIR__, "../LieGroupsTestSuite.jl")
 !(s in LOAD_PATH) && (push!(LOAD_PATH, s))
 using LieGroupsTestSuite
 
+using StaticArrays
+
 @testset "Addition Operation" begin
     @testset "Base.:+ and Base.:- with the Identity" begin
         e = Identity(AdditionGroupOperation())
@@ -17,6 +19,8 @@ using LieGroupsTestSuite
         @test (e - e) === e
         @test (-e) === e
         G = LieGroup(LieGroupsTestSuite.DummyManifold(), AdditionGroupOperation())
-        @test identity_element(G, 1.0) == 0.0
+        @test identity_element(G, Float64) == 0.0
+        @test identity_element(G, Array{Float64,0}) == fill(0.0)
+        @test identity_element(G, SArray{Tuple{},Float64}) == @SArray fill(0.0)
     end
 end