A few Kronecker fixes (#133)

Author: dkarrasch

Project.toml

@@ -1,6 +1,6 @@
 name = "LinearMaps"
 uuid = "7a12625a-238d-50fd-b39a-03d52299707e"
-version = "3.1.0"
+version = "3.2.0"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

docs/src/history.md

@@ -1,5 +1,10 @@
 # Version history
 
+## What's new in v3.2
+
+* In-place left-multiplication `mul!(Y, X, A::LinearMap)` is now allowed for
+  `X::AbstractMatrix` and implemented via the adjoint equation `Y' = A'X'`.
+
 ## What's new in v3.1
 
 * In Julia v1.3 and above, `LinearMap`-typed objects are callable on `AbstractVector`s:

src/kronecker.jl

@@ -52,9 +52,14 @@ Base.kron(A::KroneckerMap, B::LinearMap) =
     KroneckerMap{promote_type(eltype(A), eltype(B))}(tuple(A.maps..., B))
 Base.kron(A::KroneckerMap, B::KroneckerMap) =
     KroneckerMap{promote_type(eltype(A), eltype(B))}(tuple(A.maps..., B.maps...))
+# hoist out scalings
 Base.kron(A::ScaledMap, B::LinearMap) = A.λ * kron(A.lmap, B)
-Base.kron(A::LinearMap{<:RealOrComplex}, B::ScaledMap) = B.λ * kron(A, B.lmap)
+Base.kron(A::LinearMap, B::ScaledMap) = kron(A, B.lmap) * B.λ
 Base.kron(A::ScaledMap, B::ScaledMap) = (A.λ * B.λ) * kron(A.lmap, B.lmap)
+# disambiguation
+Base.kron(A::ScaledMap, B::KroneckerMap) = A.λ * kron(A.lmap, B)
+Base.kron(A::KroneckerMap, B::ScaledMap) = kron(A, B.lmap) * B.λ
+# generic definitions
 Base.kron(A::LinearMap, B::LinearMap, C::LinearMap, Ds::LinearMap...) =
     kron(kron(A, B), C, Ds...)
 Base.kron(A::AbstractMatrix, B::LinearMap) = kron(LinearMap(A), B)

test/kronecker.jl

@@ -12,6 +12,8 @@ using Test, LinearMaps, LinearAlgebra, SparseArrays
         @test kron(3LA, LB) isa LinearMaps.ScaledMap
         @test kron(3LA, 2LB) isa LinearMaps.ScaledMap
         @test kron(3LA, 2LB).λ == 6
+        @test kron(kron(LA, LA), 2LB) isa LinearMaps.ScaledMap
+        @test kron(3LA, kron(LB, LB)) isa LinearMaps.ScaledMap
         @test_throws ErrorException LinearMaps.KroneckerMap{Float64}((LA, LB))
         @test occursin("6×6 LinearMaps.KroneckerMap{$(eltype(LK))}", sprint((t, s) -> show(t, "text/plain", s), LK))
         @test @inferred size(LK) == size(K)

test/wrappedmap.jl

@@ -6,6 +6,7 @@ using Test, LinearMaps, LinearAlgebra
     SA = A'A + I
     SB = B'B + I
     L = @inferred LinearMap{Float64}(A)
+    @test summary(L) == "10×20 LinearMaps.WrappedMap{Float64}"
     @test occursin("10×20 LinearMaps.WrappedMap{Float64}", sprint((t, s) -> show(t, "text/plain", s), L))
     MA = @inferred LinearMap(SA)
     MB = @inferred LinearMap(SB)