fix QR non-square handling

Author: ChrisRackauckas

src/LinearSolve.jl

@@ -58,6 +58,6 @@ export LinearSolveFunction
 export KrylovJL, KrylovJL_CG, KrylovJL_GMRES, KrylovJL_BICGSTAB, KrylovJL_MINRES,
        IterativeSolversJL, IterativeSolversJL_CG, IterativeSolversJL_GMRES,
        IterativeSolversJL_BICGSTAB, IterativeSolversJL_MINRES,
-       KrylovKitJL, KrylovKitJL_CG, KrylovKitJL_GMRES
+       KrylovKitJL, KrylovKitJL_CG, KrylovKitJL_GMRES, KrylovJL_LSMR
 
 end

src/factorization.jl

@@ -5,6 +5,11 @@ function _ldiv!(x::Vector, A::Factorization, b::Vector)
     ldiv!(A, x)
 end
 
+# Specialize QR for the non-square case
+function _ldiv!(x::Vector, A::QRFactorization, b::Vector)
+    ldiv!(x, A, b)
+end
+
 function SciMLBase.solve(cache::LinearCache, alg::AbstractFactorization; kwargs...)
     if cache.isfresh
         fact = do_factorization(alg, cache.A, cache.b, cache.u)

test/nonsquare.jl

@@ -0,0 +1,7 @@
+using LinearSolve
+using SparseArrays, LinearAlgebra
+
+m, n = 13, 3
+A = sprand(m, n, 0.5); b = rand(m);
+prob = LinearProblem(A, b)
+solve(prob)

test/runtests.jl

@@ -21,6 +21,7 @@ end
 if GROUP == "All" || GROUP == "Core"
     @time @safetestset "Basic Tests" begin include("basictests.jl") end
     @time @safetestset "Zero Initialization Tests" begin include("zeroinittests.jl") end
+    @time @safetestset "Non-Square Tests" begin include("nonsquare.jl") end
 end
 
 if GROUP == "LinearSolveCUDA"