From c7c34aa3c1ebb5ca35e335ed4d420596279469ca Mon Sep 17 00:00:00 2001
From: Jishnu Bhattacharya <jishnub.github@gmail.com>
Date: Tue, 12 Dec 2023 18:02:23 +0530
Subject: [PATCH] Specalize `istriu`/`istril` (#326)

* Specalize isdiag and istriu/istril

* Remove isdiag specialization
---
 Project.toml       |  2 +-
 src/fillalgebra.jl |  8 ++++++++
 test/runtests.jl   | 13 +++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index fa5e2996..06ba0f13 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "FillArrays"
 uuid = "1a297f60-69ca-5386-bcde-b61e274b549b"
-version = "1.9.3"
+version = "1.10.0"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
diff --git a/src/fillalgebra.jl b/src/fillalgebra.jl
index c4331f9d..0fef9a97 100644
--- a/src/fillalgebra.jl
+++ b/src/fillalgebra.jl
@@ -516,3 +516,11 @@ function kron(f::AbstractFillVecOrMat, g::AbstractFillVecOrMat)
     sz = _kronsize(f, g)
     return _kron(f, g, sz)
 end
+
+# bandedness
+function LinearAlgebra.istriu(A::AbstractFillMatrix, k::Integer = 0)
+    iszero(A) || k <= -(size(A,1)-1)
+end
+function LinearAlgebra.istril(A::AbstractFillMatrix, k::Integer = 0)
+    iszero(A) || k >= size(A,2)-1
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index 2e132622..0de16a98 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -2370,3 +2370,16 @@ end
         @test a.value == first(diag)
     end
 end
+
+@testset "isbanded/isdiag" begin
+    @testset for A in Any[Zeros(2,3), Zeros(0,1), Zeros(1,1), Zeros(1,2),
+            Ones(0,1), Ones(1,1), Ones(3,4), Ones(0,4), Ones(7,0), Ones(7,2), Ones(2,7),
+            Fill(3, 0,1), Fill(3, 1,1), Fill(3, 2,4), Fill(0, 3, 4), Fill(2, 0, 4), Fill(2, 6, 0), Fill(0, 8, 8)]
+        B = Array(A)
+        @test isdiag(A) == isdiag(B)
+        for k in -5:5
+            @test istriu(A, k) == istriu(B, k)
+            @test istril(A, k) == istril(B, k)
+        end
+    end
+end