Fix 0-index Euclidean just like Circle (#697)

NEWS.md

@@ -5,6 +5,12 @@ 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).
 
+## [0.9.11] – 2023-12-27
+
+### Fixed
+
+* Fixed mixed array index number in-place `parallel_transport_to!` on zero-index `Euclidean`, on Julia 1.6.
+
 ## [0.9.10] – 2023-12-27
 
 ### Added

Project.toml

@@ -1,7 +1,7 @@
 name = "Manifolds"
 uuid = "1cead3c2-87b3-11e9-0ccd-23c62b72b94e"
 authors = ["Seth Axen <seth.axen@gmail.com>", "Mateusz Baran <mateuszbaran89@gmail.com>", "Ronny Bergmann <manopt@ronnybergmann.net>", "Antoine Levitt <antoine.levitt@gmail.com>"]
-version = "0.9.10"
+version = "0.9.11"
 
 [deps]
 Distributions = "31c24e10-a181-5473-b8eb-7969acd0382f"

src/manifolds/Euclidean.jl

@@ -213,6 +213,8 @@ Base.exp(::Euclidean, p, X, t::Number) = p .+ t .* X
 
 exp!(::Euclidean, q, p, X) = (q .= p .+ X)
 exp!(::Euclidean, q, p, X, t::Number) = (q .= p .+ t .* X)
+exp!(::Euclidean{TypeParameter{Tuple{}}}, q, p, X, t::Number) = (q .= p[] + t * X[])
+exp!(::Euclidean{Tuple{}}, q, p, X, t::Number) = (q .= p[] + t * X[])
 
 function get_basis_diagonalizing(
     M::Euclidean,
@@ -677,6 +679,10 @@ the parallel transport on [`Euclidean`](@ref) is the identiy, i.e. returns `X`.
 """
 parallel_transport_to(::Euclidean, ::Any, X, ::Any) = X
 parallel_transport_to!(::Euclidean, Y, ::Any, X, ::Any) = copyto!(Y, X)
+function parallel_transport_to!(::Euclidean{TypeParameter{Tuple{}}}, Y, ::Any, X, ::Any)
+    return copyto!(Y, X[])
+end
+parallel_transport_to!(::Euclidean{Tuple{}}, Y, ::Any, X, ::Any) = copyto!(Y, X[])
 
 @doc raw"""
     project(M::Euclidean, p)

test/manifolds/euclidean.jl

@@ -446,4 +446,15 @@ using FiniteDifferences
             ManifoldDiff.βdifferential_shortest_geodesic_startpoint,
         ) === 2.0
     end
+
+    @testset "Mixed array dimensions for exp and PT" begin
+        # this is an issue on Julia 1.6 but not later releases
+        for M in [Euclidean(), Euclidean(; parameter=:field)]
+            p = fill(0.0)
+            exp!(M, p, p, [1.0], 2.0)
+            @test p ≈ fill(2.0)
+            parallel_transport_to!(M, p, p, [4.0], p)
+            @test p ≈ fill(4.0)
+        end
+    end
 end