make mutable copies in reversecholcopy

Project.toml

@@ -1,6 +1,6 @@
 name = "MatrixFactorizations"
 uuid = "a3b82374-2e81-5b9e-98ce-41277c0e4c87"
-version = "2.0"
+version = "2.0.1"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/MatrixFactorizations.jl

@@ -10,7 +10,7 @@ import LinearAlgebra: cholesky, cholesky!, norm, diag, eigvals!, eigvals, eigen!
    chkstride1, kron, lmul!, rmul!, factorize, StructuredMatrixStyle, det, logabsdet,
    AbstractQ, _zeros, _cut_B, _ret_size, require_one_based_indexing, checksquare,
    checknonsingular, ipiv2perm, copytri!, issuccess, RealHermSymComplexHerm,
-   cholcopy, checkpositivedefinite, char_uplo
+   cholcopy, checkpositivedefinite, char_uplo, copymutable_oftype
 
 import Base: getindex, setindex!, *, +, -, ==, <, <=, >,
    >=, /, ^, \, transpose, showerror, reindex, checkbounds, @propagate_inbounds

src/reversecholesky.jl

@@ -139,24 +139,22 @@ end
 reversecholcopy(A) = cholcopy(A)
 function reversecholcopy(A::SymTridiagonal)
     T = LinearAlgebra.choltype(A)
-    Symmetric(Bidiagonal(AbstractVector{T}(A.dv), AbstractVector{T}(A.ev), :U))
+    Symmetric(Bidiagonal(copymutable_oftype(A.dv, T), copymutable_oftype(A.ev, T), :U))
 end
 
 function reversecholcopy(A::Symmetric{<:Any,<:Tridiagonal})
     T = LinearAlgebra.choltype(A)
     if A.uplo == 'U'
-        Symmetric(Bidiagonal(AbstractVector{T}(parent(A).d), AbstractVector{T}(parent(A).du), :U))
+        Symmetric(Bidiagonal(copymutable_oftype(parent(A).d, T), copymutable_oftype(parent(A).du, T), :U))
     else
-        Symmetric(Bidiagonal(AbstractVector{T}(parent(A).d), AbstractVector{T}(parent(A).dl), :L), :L)
+        Symmetric(Bidiagonal(copymutable_oftype(parent(A).d, T), copymutable_oftype(parent(A).dl, T), :L), :L)
     end
 end
 
-_copyifsametype(::Type{T}, A::AbstractMatrix{T}) where T = copy(A)
-_copyifsametype(_, A) = A
 
 function reversecholcopy(A::Symmetric{<:Any,<:Bidiagonal})
     T = LinearAlgebra.choltype(A)
-    B = _copyifsametype(T, AbstractMatrix{T}(parent(A)))
+    B = copymutable_oftype(parent(A), T)
     Symmetric{T,typeof(B)}(B, A.uplo)
 end
 

test/test_reversecholesky.jl

@@ -3,6 +3,7 @@
 using Test, LinearAlgebra, Random, MatrixFactorizations
 using LinearAlgebra: BlasComplex, BlasFloat, BlasReal, QRPivoted,
     PosDefException, RankDeficientException, chkfullrank
+using ArrayLayouts: Fill
 
 function unary_ops_tests(a, ca, tol; n=size(a, 1))
     @test inv(ca)*a ≈ Matrix(I, n, n)
@@ -412,4 +413,11 @@ end
         @test reversecholesky(5).U[1,1] ≈ sqrt(5)
         @test propertynames(R) == (:U, :L, :UL)
     end
+
+    @testset "Lazy reversecholesky" begin
+        A = SymTridiagonal(Fill(2,10), Fill(1,9))
+        @test reversecholesky(A) == reversecholesky(SymTridiagonal(fill(2.0,10), fill(1.0,9))) == 
+                reversecholesky(Symmetric(Bidiagonal(Fill(2,10), Fill(1,9), :U))) ==
+                reversecholesky(Symmetric(Tridiagonal(Fill(3,9), Fill(2,10), Fill(1,9))))
+    end
 end