Fix Matrix(QRSparseQ) constructor

Fixes #26367

stdlib/LinearAlgebra/src/qr.jl

@@ -527,21 +527,20 @@ AbstractMatrix{T}(Q::QRPackedQ) where {T} = QRPackedQ{T}(Q)
 QRCompactWYQ{S}(Q::QRCompactWYQ) where {S} = QRCompactWYQ(convert(AbstractMatrix{S}, Q.factors), convert(AbstractMatrix{S}, Q.T))
 AbstractMatrix{S}(Q::QRCompactWYQ{S}) where {S} = Q
 AbstractMatrix{S}(Q::QRCompactWYQ) where {S} = QRCompactWYQ{S}(Q)
-Matrix(A::AbstractQ{T}) where {T} = lmul!(A, Matrix{T}(I, size(A.factors, 1), min(size(A.factors)...)))
-Array(A::AbstractQ) = Matrix(A)
+Matrix(Q::Union{QRCompactWYQ{T},QRPackedQ{T}}) where {T} = lmul!(Q, Matrix{T}(I, size(Q, 1), min(size(Q.factors)...)))
+Array(Q::AbstractQ) = Matrix(Q)
 
-size(A::Union{QR,QRCompactWY,QRPivoted}, dim::Integer) = size(getfield(A, :factors), dim)
-size(A::Union{QR,QRCompactWY,QRPivoted}) = size(getfield(A, :factors))
-size(A::AbstractQ, dim::Integer) = 0 < dim ? (dim <= 2 ? size(getfield(A, :factors), 1) : 1) : throw(BoundsError())
-size(A::AbstractQ) = size(A, 1), size(A, 2)
+size(F::Union{QR,QRCompactWY,QRPivoted}, dim::Integer) = size(getfield(F, :factors), dim)
+size(F::Union{QR,QRCompactWY,QRPivoted}) = size(getfield(F, :factors))
+size(Q::Union{QRCompactWYQ,QRPackedQ}, dim::Integer) = size(getfield(Q, :factors), dim == 2 ? 1 : dim)
+size(Q::AbstractQ) = size(Q, 1), size(Q, 2)
 
-
-function getindex(A::AbstractQ, i::Integer, j::Integer)
-    x = zeros(eltype(A), size(A, 1))
+function getindex(Q::AbstractQ, i::Integer, j::Integer)
+    x = zeros(eltype(Q), size(Q, 1))
     x[i] = 1
-    y = zeros(eltype(A), size(A, 2))
+    y = zeros(eltype(Q), size(Q, 2))
     y[j] = 1
-    return dot(x, lmul!(A, y))
+    return dot(x, lmul!(Q, y))
 end
 
 ## Multiplication by Q

stdlib/LinearAlgebra/test/qr.jl

@@ -146,7 +146,7 @@ rectangularQ(Q::LinearAlgebra.AbstractQ) = convert(Array, Q)
                 @test_throws DimensionMismatch rmul!(Matrix{eltya}(I, n+1, n+1),q)
                 @test rmul!(squareQ(q), adjoint(q)) ≈ Matrix(I, n, n)
                 @test_throws DimensionMismatch rmul!(Matrix{eltya}(I, n+1, n+1), adjoint(q))
-                @test_throws BoundsError size(q,-1)
+                @test_throws ErrorException size(q,-1)
                 @test_throws DimensionMismatch LinearAlgebra.lmul!(q,zeros(eltya,n1+1))
                 @test_throws DimensionMismatch LinearAlgebra.lmul!(adjoint(q), zeros(eltya,n1+1))
 
@@ -156,7 +156,7 @@ rectangularQ(Q::LinearAlgebra.AbstractQ) = convert(Array, Q)
                 @test_throws DimensionMismatch rmul!(Matrix{eltya}(I, n+1, n+1),q)
                 @test rmul!(squareQ(q), adjoint(q)) ≈ Matrix(I, n, n)
                 @test_throws DimensionMismatch rmul!(Matrix{eltya}(I, n+1, n+1),adjoint(q))
-                @test_throws BoundsError size(q,-1)
+                @test_throws ErrorException size(q,-1)
                 @test_throws DimensionMismatch q * Matrix{Int8}(I, n+4, n+4)
             end
         end

stdlib/SuiteSparse/src/spqr.jl

@@ -128,10 +128,13 @@ end
 struct QRSparseQ{Tv<:CHOLMOD.VTypes,Ti<:Integer} <: LinearAlgebra.AbstractQ{Tv}
     factors::SparseMatrixCSC{Tv,Ti}
     τ::Vector{Tv}
+    n::Int # Number of columns in original matrix
 end
 
 Base.size(Q::QRSparseQ) = (size(Q.factors, 1), size(Q.factors, 1))
 
+Matrix(Q::QRSparseQ) where {T} = lmul!(A, Matrix{T}(I, size(Q, 1), min(size(Q, 1), Q.n)))
+
 # From SPQR manual p. 6
 _default_tol(A::SparseMatrixCSC) =
     20*sum(size(A))*eps(real(eltype(A)))*maximum(norm(view(A, :, i))^2 for i in 1:size(A, 2))
@@ -303,7 +306,7 @@ julia> F.pcol
 """
 @inline function Base.getproperty(F::QRSparse, d::Symbol)
     if d == :Q
-        return QRSparseQ(F.factors, F.τ)
+        return QRSparseQ(F.factors, F.τ, size(F, 2))
     elseif d == :prow
         return invperm(F.rpivinv)
     elseif d == :pcol

stdlib/SuiteSparse/test/spqr.jl

@@ -81,4 +81,9 @@ end
     @test A*xs ≈ A*xd
 end
 
+@testset "Issue 26367" begin
+    A = sparse([0.0 1 0 0; 0 0 0 0])
+    @test Matrix(qrfact(A).Q) == Matrix(qrfact(Matrix(A)).Q) == Matrix(I, 2, 2)
+end
+
 end