Don't use copy_oftype in \(QRX, B) to make sure that solution array i…

…s mutable (#24110) * Don't use copy_oftype in \(QRX, B) to make sure that solution array is mutable. Fixes #24107 * Always return B in A_ldiv_B!(QRPivoted, B)
JuliaLang · Oct 15, 2017 · f9c662d · f9c662d
1 parent 9eebbf9
commit f9c662d
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Showing 2 changed files with 18 additions and 21 deletions.
diff --git a/base/linalg/qr.jl b/base/linalg/qr.jl
@@ -775,11 +775,12 @@ function A_ldiv_B!(A::QRPivoted{T}, B::StridedMatrix{T}, rcond::Real) where T<:B
     nr = min(mA,nA)
     nrhs = size(B, 2)
     if nr == 0
-        return zeros(T, 0, nrhs), 0
+        return B, 0
     end
     ar = abs(A.factors[1])
     if ar == 0
-        return zeros(T, nA, nrhs), 0
+        B[1:nA, :] = 0
+        return B, 0
     end
     rnk = 1
     xmin = ones(T, 1)
@@ -873,23 +874,8 @@ _cut_B(x::AbstractVector, r::UnitRange) = length(x)  > length(r) ? x[r]   : x
 _cut_B(X::AbstractMatrix, r::UnitRange) = size(X, 1) > length(r) ? X[r,:] : X
 
 ## append right hand side with zeros if necessary
-function _append_zeros(b::AbstractVector, T::Type, n)
-    if n > length(b)
-        x = zeros(T, n)
-        return copy!(x, b)
-    else
-        return copy_oftype(b, T)
-    end
-end
-function _append_zeros(B::AbstractMatrix, T::Type, n)
-    if n > size(B, 1)
-        X = zeros(T, (n, size(B, 2)))
-        X[1:size(B,1), :] = B
-        return X
-    else
-        return copy_oftype(B, T)
-    end
-end
+_zeros(::Type{T}, b::AbstractVector, n::Integer) where {T} = zeros(T, max(length(b), n))
+_zeros(::Type{T}, B::AbstractMatrix, n::Integer) where {T} = zeros(T, max(size(B, 1), n), size(B, 2))
 
 function (\)(A::Union{QR{TA},QRCompactWY{TA},QRPivoted{TA}}, B::AbstractVecOrMat{TB}) where {TA,TB}
     S = promote_type(TA,TB)
@@ -898,7 +884,10 @@ function (\)(A::Union{QR{TA},QRCompactWY{TA},QRPivoted{TA}}, B::AbstractVecOrMat
 
     AA = convert(Factorization{S}, A)
 
-    X = A_ldiv_B!(AA, _append_zeros(B, S, n))
+    X = _zeros(S, B, n)
+    X[1:size(B, 1), :] = B
+
+    A_ldiv_B!(AA, X)
 
     return _cut_B(X, 1:n)
 end
@@ -920,7 +909,10 @@ function (\)(A::Union{QR{T},QRCompactWY{T},QRPivoted{T}}, BIn::VecOrMat{Complex{
 #                                                 |x4|y4|
     B = reshape(transpose(reinterpret(T, reshape(BIn, (1, length(BIn))))), size(BIn, 1), 2*size(BIn, 2))
 
-    X = A_ldiv_B!(A, _append_zeros(B, T, n))
+    X = _zeros(T, B, n)
+    X[1:size(B, 1), :] = B
+
+    A_ldiv_B!(A, X)
 
 # |z1|z3|  reinterpret  |x1|x2|x3|x4|  transpose  |x1|y1|  reshape  |x1|y1|x3|y3|
 # |z2|z4|      <-       |y1|y2|y3|y4|     <-      |x2|y2|     <-    |x2|y2|x4|y4|

diff --git a/test/linalg/qr.jl b/test/linalg/qr.jl
@@ -197,3 +197,8 @@ end
     @test A \ B == zeros(2, 1)
     @test qrfact(A, Val(true)) \ B == zeros(2, 1)
 end
+
+@testset "Issue 24107" begin
+    A = rand(200,2)
+    @test A \ linspace(0,1,200) == A \ collect(linspace(0,1,200))
+end