Fix minimum band for UpperTriangular/Lowertriangular

Author: jishnub

src/triangular.jl

@@ -376,9 +376,9 @@ istril(A::Transpose, k::Integer=0) = istriu(A.parent, -k)
 istriu(A::Adjoint, k::Integer=0) = istril(A.parent, -k)
 istriu(A::Transpose, k::Integer=0) = istril(A.parent, -k)
 
-istril(U::UpperTriangular, k::Integer=0) = istril(parent(U), max(0, k))
+istril(U::UpperTriangular, k::Integer=0) = istril(parent(U), max(-1, k))
 istril(U::UnitUpperTriangular, k::Integer=0) = k < 0 ? false : istril(parent(U), k)
-istriu(U::LowerTriangular, k::Integer=0) = istriu(parent(U), min(0, k))
+istriu(U::LowerTriangular, k::Integer=0) = istriu(parent(U), min(1, k))
 istriu(U::UnitLowerTriangular, k::Integer=0) = k > 0 ? false : istriu(parent(U), k)
 
 function tril!(A::UpperTriangular{T}, k::Integer=0) where {T}

test/triangular.jl

@@ -196,33 +196,6 @@ end
     @test isdiag(LowerTriangular(diagm(0 => [1,2,3,4])))
     @test !isdiag(UpperTriangular(rand(4, 4)))
     @test !isdiag(LowerTriangular(rand(4, 4)))
-
-    for A in [rand(4,4), zeros(4,4), diagm(1=>1:3), diagm(-2=>2:3)]
-        U = UpperTriangular(A)
-        UA = Array(U)
-        L = LowerTriangular(A)
-        LA = Array(L)
-        UU = UnitUpperTriangular(A)
-        UUA = Array(UU)
-        UL = UnitLowerTriangular(A)
-        ULA = Array(UL)
-        for k in -size(A,1):size(A,2)
-            @test istril(U, k) == istril(UA, k)
-            @test istriu(L, k) == istriu(LA, k)
-            @test istril(UU, k) == istril(UUA, k)
-            @test istriu(UL, k) == istriu(ULA, k)
-        end
-    end
-    for (T, f) in ((UnitUpperTriangular, istril), (UnitLowerTriangular, istriu))
-        A = Matrix{BigFloat}(undef, 2, 2)
-        isupper = T === UnitUpperTriangular
-        A[1+!isupper, 1+isupper] = 3
-        UU = T(A)
-        UUA = Array(UU)
-        for k in -size(A,1):size(A,2)
-            @test f(UU, k) == f(UUA, k)
-        end
-    end
 end
 
 # Test throwing in fallbacks for non BlasFloat/BlasComplex in A_rdiv_Bx!
@@ -761,15 +734,16 @@ end
 end
 
 @testset "istriu/istril forwards to parent" begin
-    @testset "$(nameof(typeof(M)))" for M in [Tridiagonal(rand(n-1), rand(n), rand(n-1)),
+    @testset "$(nameof(typeof(M)))" for M in Any[Tridiagonal(rand(n-1), rand(n), rand(n-1)),
                 Tridiagonal(zeros(n-1), zeros(n), zeros(n-1)),
                 Diagonal(randn(n)),
                 Diagonal(zeros(n)),
+                rand(n,n), zeros(n,n), diagm(1=>1:n-1), diagm(-2=>1:n-2),
                 ]
         @testset for TriT in (UpperTriangular, UnitUpperTriangular, LowerTriangular, UnitLowerTriangular)
             U = TriT(M)
             A = Array(U)
-            for k in -n:n
+            @testset for k in -n:n
                 @test istriu(U, k) == istriu(A, k)
                 @test istril(U, k) == istril(A, k)
             end
@@ -787,6 +761,19 @@ end
         end
     end
 
+    @testset "partly initialized in unit triangular" begin
+        for (T, f) in ((UnitUpperTriangular, istril), (UnitLowerTriangular, istriu))
+            A = Matrix{BigFloat}(undef, 2, 2)
+            isupper = T === UnitUpperTriangular
+            A[1+!isupper, 1+isupper] = 3
+            UU = T(A)
+            UUA = Array(UU)
+            for k in -size(A,1):size(A,2)
+                @test f(UU, k) == f(UUA, k)
+            end
+        end
+    end
+
     @testset "Union eltype" begin
         M = Matrix{Union{Int,Missing}}(missing,2,2)
         U = triu(M)