adds a test for positive vectors and starts testing the default Metri…

…c fallbacks using the local metric.
JuliaManifolds · Sep 16, 2021 · 95a3c8b · 95a3c8b
1 parent 5005965
commit 95a3c8b
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Showing 5 changed files with 27 additions and 4 deletions.
diff --git a/src/manifolds/HyperbolicHyperboloid.jl b/src/manifolds/HyperbolicHyperboloid.jl
@@ -19,7 +19,11 @@ function change_representer!(M::Hyperbolic, Y, ::EuclideanMetric, p, X)
     return Y
 end
 
-# a metric change does not seem possible here
+function change_metric(::Hyperbolic, ::EuclideanMetric, ::Any, ::Any)
+    return error(
+        "Changing metric from Euclidean to Hyperbolic is not possible (see Sylvester's law of inertia).",
+    )
+end
 
 function check_point(M::Hyperbolic, p; kwargs...)
     mpv = invoke(check_point, Tuple{supertype(typeof(M)),typeof(p)}, M, p; kwargs...)

diff --git a/src/manifolds/MetricManifold.jl b/src/manifolds/MetricManifold.jl
@@ -177,7 +177,7 @@ function change_metric!(M::AbstractManifold, Y, G::AbstractMetric, p, X)
     # TODO: For local metric, inverse_local metric, det_local_metric: Introduce a default basis?
     B = DefaultOrthogonalBasis()
     G1 = local_metric(M, p, B)
-    G2 = localMetric(G(M), p, B)
+    G2 = local_metric(G(M), p, B)
     x = get_coordinates(M, p, X, B)
     C1 = cholesky(G1).L
     C2 = cholesky(G2).L

diff --git a/test/manifolds/hyperbolic.jl b/test/manifolds/hyperbolic.jl
@@ -269,7 +269,7 @@ include("../utils.jl")
         Y = change_representer(M, EuclideanMetric(), p, X)
         @test inner(M, p, X, Y) == inner(Euclidean(3), p, X, X)
         # change metric not possible from Euclidean, since the embedding is Lorenzian
-        @test_throws MethodError change_metric(M, EuclideanMetric(), p, X)
+        @test_throws ErrorException change_metric(M, EuclideanMetric(), p, X)
         # but if we come from the same metric, we have the identity
         @test change_metric(M, MinkowskiMetric(), p, X) == X
     end

diff --git a/test/manifolds/positive_numbers.jl b/test/manifolds/positive_numbers.jl
@@ -26,6 +26,9 @@ include("../utils.jl")
 
         @test change_metric(M, EuclideanMetric(), 2, 3) == 3 * 2
         @test change_representer(M, EuclideanMetric(), 2, 3) == 3 * 2^2
+        N = PositiveVectors(2)
+        @test change_metric(M, EuclideanMetric(), [1, 2], [3, 4]) == [3, 4 * 2]
+        @test change_representer(M, EuclideanMetric(), [1, 2], [3, 4]) == [3, 4 * 2^2]
     end
     types = [Float64]
     TEST_FLOAT32 && push!(types, Float32)

diff --git a/test/metric.jl b/test/metric.jl
@@ -7,6 +7,7 @@ include("utils.jl")
 
 struct TestEuclidean{N} <: AbstractManifold{ℝ} end
 struct TestEuclideanMetric <: AbstractMetric end
+struct TestScaledEuclideanMetric <: AbstractMetric end
 
 Manifolds.manifold_dimension(::TestEuclidean{N}) where {N} = N
 function Manifolds.local_metric(
@@ -19,10 +20,17 @@ end
 function Manifolds.local_metric(
     M::MetricManifold{ℝ,<:TestEuclidean,<:TestEuclideanMetric},
     ::Any,
-    ::InducedBasis,
+    ::DefaultOrthonormalBasis,
 )
     return Diagonal(1.0:manifold_dimension(M))
 end
+function Manifolds.local_metric(
+    M::MetricManifold{ℝ,<:TestEuclidean,<:TestScaledEuclideanMetric},
+    ::Any,
+    ::DefaultOrthonormalBasis,
+)
+    return 2 .* Diagonal(1.0:manifold_dimension(M))
+end
 
 struct TestSphere{N,T} <: AbstractManifold{ℝ}
     r::T
@@ -603,4 +611,12 @@ end
             ExponentialRetraction(),
         ) === Val{:parent}()
     end
+
+    @testset "change metric and representer" begin
+        M = MetricManifold(TestEuclidean{2}(), TestEuclideanMetric())
+        G = TestScaledEuclideanMetric()
+        p = ones(2)
+        X = 2 * ones(2)
+        Y = change_metric(M, G, p, X)
+    end
 end