From 30c32a45c09bbced44fbfee86ba1b222adedd3da Mon Sep 17 00:00:00 2001
From: Jishnu Bhattacharya <jishnub.github@gmail.com>
Date: Sun, 14 Apr 2024 18:48:32 +0530
Subject: [PATCH 1/3] Extend copytrito! for a sparse source

---
 src/SparseArrays.jl      |  2 +-
 src/sparsematrix.jl      | 24 ++++++++++++++++++++++++
 test/sparsematrix_ops.jl | 24 ++++++++++++++++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/src/SparseArrays.jl b/src/SparseArrays.jl
index ff554c8e..84690b95 100644
--- a/src/SparseArrays.jl
+++ b/src/SparseArrays.jl
@@ -18,7 +18,7 @@ import Base: +, -, *, \, /, &, |, xor, ==, zero, @propagate_inbounds
 import LinearAlgebra: mul!, ldiv!, rdiv!, cholesky, adjoint!, diag, eigen, dot,
     issymmetric, istril, istriu, lu, tr, transpose!, tril!, triu!, isbanded,
     cond, diagm, factorize, ishermitian, norm, opnorm, lmul!, rmul!, tril, triu,
-    matprod_dest, generic_matvecmul!, generic_matmatmul!
+    matprod_dest, generic_matvecmul!, generic_matmatmul!, copytrito!
 
 import Base: adjoint, argmin, argmax, Array, broadcast, circshift!, complex, Complex,
     conj, conj!, convert, copy, copy!, copyto!, count, diff, findall, findmax, findmin,
diff --git a/src/sparsematrix.jl b/src/sparsematrix.jl
index b9637eda..363abff1 100644
--- a/src/sparsematrix.jl
+++ b/src/sparsematrix.jl
@@ -4540,3 +4540,27 @@ function _reverse!(A::SparseMatrixCSC, dims::Tuple{Integer,Integer})
     dims == (1,2) || dims == (2,1) || throw(ArgumentError("invalid dimension $dims in reverse"))
     _reverse!(A, :)
 end
+
+function copytrito!(M::AbstractMatrix, S::AbstractSparseMatrixCSC, uplo::Char)
+    Base.require_one_based_indexing(M, S)
+    if !(uplo == 'U' || uplo == 'L')
+        throw(ArgumentError(lazy"uplo argument must be 'U' (upper) or 'L' (lower), got '$uplo'"))
+    end
+    m,n = size(S)
+    m1,n1 = size(M)
+    (m1 < m || n1 < n) && throw(DimensionMismatch("dest of size ($m1,$n1) should have at least the same number of rows and columns than src of size ($m,$n)"))
+
+    rv = rowvals(S)
+    nz = nonzeros(S)
+    for col in axes(S,2)
+        trirange = uplo == 'U' ? (1:min(col, size(S,1))) : (col:size(S,1))
+        fill!(view(M, trirange, col), zero(eltype(S)))
+        for i in nzrange(S, col)
+            row = rv[i]
+            (uplo == 'U' && row <= col) || (uplo == 'L' && row >= col) || continue
+            v = nz[i]
+            M[row, col] = v 
+        end
+    end 
+    return M
+end
diff --git a/test/sparsematrix_ops.jl b/test/sparsematrix_ops.jl
index 829baf89..2d3562bd 100644
--- a/test/sparsematrix_ops.jl
+++ b/test/sparsematrix_ops.jl
@@ -601,4 +601,28 @@ end
     end
 end
 
+@testset "copytrito!" begin
+    S = sparse([1,2,2,2,3], [1,1,2,2,4], [5, -19, 73, 12, -7])
+    M = fill(Inf, size(S))
+    copytrito!(M, S, 'U')
+    for col in axes(S, 2)
+        for row in 1:min(col, size(S,1))
+            @test M[row, col] == S[row, col]
+        end
+        for row in min(col, size(S,1))+1:size(S,1)
+            @test isinf(M[row, col])
+        end
+    end
+    M .= Inf
+    copytrito!(M, S, 'L')
+    for col in axes(S, 2)
+        for row in 1:col-1
+            @test isinf(M[row, col])
+        end
+        for row in col:size(S, 1)
+            @test M[row, col] == S[row, col]
+        end
+    end
+end
+
 end # module

From f921966a6e9bc91d360c22d1017e97eb17bafb2e Mon Sep 17 00:00:00 2001
From: Jishnu Bhattacharya <jishnub.github@gmail.com>
Date: Mon, 15 Apr 2024 11:52:31 +0530
Subject: [PATCH 2/3] Test for invalid uplo

---
 test/sparsematrix_ops.jl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/sparsematrix_ops.jl b/test/sparsematrix_ops.jl
index 2d3562bd..94e268e0 100644
--- a/test/sparsematrix_ops.jl
+++ b/test/sparsematrix_ops.jl
@@ -623,6 +623,7 @@ end
             @test M[row, col] == S[row, col]
         end
     end
+    @test_throws ArgumentError copytrito!(M, S, 'M')
 end
 
 end # module

From 16076cda80cd378f0c29eff881286c1da898222b Mon Sep 17 00:00:00 2001
From: Jishnu Bhattacharya <jishnub.github@gmail.com>
Date: Mon, 15 Apr 2024 18:36:52 +0530
Subject: [PATCH 3/3] Assign nz[i] directly

---
 src/sparsematrix.jl | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/sparsematrix.jl b/src/sparsematrix.jl
index 363abff1..f94318b2 100644
--- a/src/sparsematrix.jl
+++ b/src/sparsematrix.jl
@@ -4558,8 +4558,7 @@ function copytrito!(M::AbstractMatrix, S::AbstractSparseMatrixCSC, uplo::Char)
         for i in nzrange(S, col)
             row = rv[i]
             (uplo == 'U' && row <= col) || (uplo == 'L' && row >= col) || continue
-            v = nz[i]
-            M[row, col] = v 
+            M[row, col] = nz[i]
         end
     end 
     return M