type conversions

ensure that the factorization works for the identity

Author: MikaelSlevinsky

src/lulinv.jl

@@ -73,6 +73,7 @@ end
 
 LULinv(factors::AbstractMatrix{T}) where T = LULinv{T, typeof(factors)}(factors)
 LULinv{T}(factors::AbstractMatrix) where T = LULinv(convert(AbstractMatrix{T}, factors))
+LULinv{T}(F::LULinv) where T = LULinv{T}(F.factors)
 
 iterate(F::LULinv) = (F.L, Val(:U))
 iterate(F::LULinv, ::Val{:U}) = (F.U, Val(:done))
@@ -166,8 +167,10 @@ function lulinv!(A::Matrix{T}, λ::Vector{T}; rtol::Real = size(A, 1)*eps(real(f
                         push!(idx, k)
                     end
                 end
-                v[idx.+(i-1)] .= -F.L[idx, 1]
-                ldiv!(LowerTriangular(view(F.L, idx, idx)), view(v, idx.+(i-1)))
+                if !isempty(idx)
+                    v[idx.+(i-1)] .= -F.L[idx, 1]
+                    ldiv!(LowerTriangular(view(F.L, idx, idx)), view(v, idx.+(i-1)))
+                end
                 deleteat!(λ, j)
                 break
             end

test/test_lulinv.jl

@@ -86,19 +86,19 @@ using LinearAlgebra, MatrixFactorizations, Random, Test
     end
     @testset "REPL printing" begin
             bf = IOBuffer()
-            show(bf, "text/plain", lulinv([2 1; 1 2]))
+            show(bf, "text/plain", lulinv([1 0; 0 1]))
             seekstart(bf)
             @test String(take!(bf)) ==
 """
 LULinv{Float64, Matrix{Float64}}
 L factor:
 2×2 Matrix{Float64}:
-  1.0  0.0
- -1.0  1.0
+ 1.0  0.0
+ 0.0  1.0
 U factor:
 2×2 Matrix{Float64}:
- 1.0  1.0
- 0.0  3.0"""
+ 1.0  0.0
+ 0.0  1.0"""
     end
     @testset "propertynames" begin
         names = sort!(collect(string.(Base.propertynames(lulinv([2 1; 1 2])))))
@@ -110,5 +110,7 @@ U factor:
         A = [-150 334 778; -89 195 464; 5 -10 -27]
         F = lulinv(A, [17, -2, 3//1])
         @test A * F.L == F.L * F.U
+        G = LULinv{Float64}(F)
+        @test A * G.L ≈ G.L * G.U
     end
 end