revert changes

Author: lkdvos

src/common/pullbacks.jl

@@ -11,22 +11,5 @@ function iszerotangent end
 iszerotangent(::Any) = false
 iszerotangent(::Nothing) = true
 
-# Solve the Sylvester equation A*X + X*B + C = 0.
-# When A === B (same Hermitian PD matrix, as in polar pullbacks), use an
-# eigendecomposition-based solver to avoid LAPACK's trsyl! failing with
-# LAPACKException(1) for close eigenvalues.
-function _sylvester(A, B, C)
-    if A === B
-        return _sylvester_symm(A, C)
-    end
-    return LinearAlgebra.sylvester(A, B, C)
-end
-
-function _sylvester_symm(P, C)
-    D, Q = LinearAlgebra.eigen(LinearAlgebra.Hermitian(P))
-    Y = Q' * C * Q
-    @inbounds for j in axes(Y, 2), i in axes(Y, 1)
-        Y[i, j] = -Y[i, j] / (D[i] + D[j])
-    end
-    return Q * Y * Q'
-end
+# fallback
+_sylvester(A, B, C) = LinearAlgebra.sylvester(A, B, C)

test/testsuite/enzyme.jl

@@ -105,7 +105,6 @@ function test_enzyme(T::Type, sz; kwargs...)
             test_enzyme_polar(T, sz; kwargs...)
             test_enzyme_orthnull(T, sz; kwargs...)
         end
-        test_enzyme_projections(T, sz; kwargs...)
     end
 end
 
@@ -463,41 +462,3 @@ function test_enzyme_orthnull(
         end
     end
 end
-
-function test_enzyme_projections(
-        T::Type, sz;
-        atol::Real = 0, rtol::Real = precision(T),
-        kwargs...
-    )
-    summary_str = testargs_summary(T, sz)
-    return @testset "Projections Enzyme AD rules $summary_str" begin
-        A = instantiate_matrix(T, sz)
-        m, n = size(A)
-        fdm = eltype(T) <: Union{Float32, ComplexF32} ? EnzymeTestUtils.FiniteDifferences.central_fdm(5, 1, max_range = 1.0e-2) : EnzymeTestUtils.FiniteDifferences.central_fdm(5, 1)
-        if m == n
-            @testset "project_hermitian" begin
-                @testset "reverse: RT $RT, TA $TA" for RT in (Duplicated,), TA in (Duplicated,)
-                    Aₕ, ΔAₕ = ad_project_hermitian_setup(A)
-                    eltype(T) <: BlasFloat && test_reverse(project_hermitian, RT, (A, TA); atol, rtol, output_tangent = ΔAₕ, fdm)
-                    is_cpu(A) && enz_test_pullbacks_match(rng, project_hermitian!, project_hermitian, A, Aₕ, ΔAₕ)
-                end
-            end
-            @testset "project_antihermitian" begin
-                @testset "reverse: RT $RT, TA $TA" for RT in (Duplicated,), TA in (Duplicated,)
-                    Aₐ, ΔAₐ = ad_project_antihermitian_setup(A)
-                    eltype(T) <: BlasFloat && test_reverse(project_antihermitian, RT, (A, TA); atol, rtol, output_tangent = ΔAₐ, fdm)
-                    is_cpu(A) && enz_test_pullbacks_match(rng, project_antihermitian!, project_antihermitian, A, Aₐ, ΔAₐ)
-                end
-            end
-        end
-        if m > n
-            @testset "project_isometric" begin
-                @testset "reverse: RT $RT, TA $TA" for RT in (Duplicated,), TA in (Duplicated,)
-                    W, ΔW = ad_project_isometric_setup(A)
-                    eltype(T) <: BlasFloat && test_reverse(project_isometric, RT, (A, TA); atol, rtol, output_tangent = ΔW, fdm)
-                    is_cpu(A) && enz_test_pullbacks_match(rng, project_isometric!, project_isometric, A, W, ΔW)
-                end
-            end
-        end
-    end
-end