Support log for Hermitian CuMatrix (#2993)

* Support log for Hermitian CuMatrix

* Fix collection to host

* Fix ambiguities

Author: kshyatt

lib/cusolver/linalg.jl

@@ -165,6 +165,29 @@ for func in (:(Base.exp), :(Base.cos), :(Base.sin), :(Base.tan), :(Base.cosh), :
     end
 end
 
+for wrap_T in (:Hermitian, :Symmetric)
+    @eval begin
+        function Base.log(A::$wrap_T{T, <:StridedCuMatrix}) where {T<:BlasReal}
+            F = eigen(A)
+            if all(λ -> λ ≥ 0, F.values)
+                retmat = (F.vectors * Diagonal(log.(F.values))) * F.vectors'
+                return $wrap_T(retmat)
+            else
+                return (F.vectors * Diagonal(log.(complex.(F.values)))) * F.vectors'
+            end
+        end
+    end
+end
+function Base.log(A::Hermitian{T, <:StridedCuMatrix{T}}) where {T<:Complex}
+    F = eigen(A)
+    if all(λ -> λ ≥ 0, F.values)
+        retmat = (F.vectors * Diagonal(log.(F.values))) * F.vectors'
+        return Hermitian(retmat)
+    else
+        return (F.vectors * Diagonal(log.(complex.(F.values)))) * F.vectors'
+    end
+end
+
 # factorizations
 
 using LinearAlgebra: Factorization, AbstractQ, QRCompactWY, QRCompactWYQ, QRPackedQ

test/libraries/cusolver/dense.jl

@@ -953,6 +953,10 @@ end
     @testset for func in (exp, cos, sin, tan, cosh, sinh, tanh, atan, asinh)
         @test Array(func(d_Ah)) ≈ func(Ah)
     end
+    @test Array(parent(log(Hermitian(d_Ah)))) ≈ log(Hermitian(Ah))
+    if elty <: Real
+        @test Array(parent(log(Symmetric(d_Ah)))) ≈ log(Symmetric(Ah))
+    end
     @static if VERSION >= v"1.11.0" # not supported on 1.10 or for Complex
         if elty <: Real
             @testset for func in (cbrt,) # have to dispatch explicitly