Overload simplifiable for ∞-KronTrav multiplication (#139)

* Overload simplifiable for ∞-KronTrav multiplication

* Update test_lazybandedinf.jl

Author: dlfivefifty

ext/LazyBandedMatricesInfiniteArraysExt.jl

@@ -8,7 +8,7 @@ import LazyBandedMatrices: _krontrav_axes, _block_interlace_axes, _broadcast_sub
 import InfiniteArrays: InfFill, TridiagonalToeplitzLayout, BidiagonalToeplitzLayout, LazyArrayStyle, OneToInf
 import LazyBandedMatrices.ArrayLayouts: MemoryLayout, sublayout, RangeCumsum, Mul
 import LazyBandedMatrices.BlockArrays: sizes_from_blocks, BlockedOneTo, BlockSlice1, BlockSlice
-import LazyBandedMatrices.LazyArrays: BroadcastBandedLayout, AbstractPaddedLayout
+import LazyBandedMatrices.LazyArrays: BroadcastBandedLayout, AbstractPaddedLayout, simplifiable
 
 const OneToInfCumsum = RangeCumsum{Int,OneToInf{Int}}
 
@@ -39,6 +39,7 @@ MemoryLayout(::Type{<:KronTrav{<:Any,2,<:Any,NTuple{2,BlockedOneTo{Int,OneToInfC
 sublayout(::InfKronTravBandedBlockBandedLayout, ::Type{<:NTuple{2,BlockSlice1}}) = BroadcastBandedLayout{typeof(*)}()
 sublayout(::InfKronTravBandedBlockBandedLayout, ::Type{<:NTuple{2,BlockSlice{BlockRange{1,Tuple{OneTo{Int}}}}}}) = KronTravBandedBlockBandedLayout()
 
+simplifiable(::Mul{InfKronTravBandedBlockBandedLayout, InfKronTravBandedBlockBandedLayout}) = Val(true)
 copy(M::Mul{InfKronTravBandedBlockBandedLayout, InfKronTravBandedBlockBandedLayout}) = KronTrav((krontravargs(M.A) .* krontravargs(M.B))...)
 
 _broadcast_sub_arguments(::InfKronTravBandedBlockBandedLayout, M, V) = _broadcast_sub_arguments(KronTravBandedBlockBandedLayout(), M, V)

test/test_lazybandedinf.jl

@@ -2,7 +2,7 @@ using LazyBandedMatrices, InfiniteArrays, ArrayLayouts, LazyArrays, BlockArrays,
 using InfiniteArrays: TridiagonalToeplitzLayout, BidiagonalToeplitzLayout, TridiagonalToeplitzLayout
 using Base: oneto
 using BlockArrays: blockcolsupport
-using LazyArrays: arguments
+using LazyArrays: arguments, simplifiable
 using LazyBandedMatrices: BroadcastBandedBlockBandedLayout
 
 const InfiniteArraysBlockArraysExt = Base.get_extension(InfiniteArrays, :InfiniteArraysBlockArraysExt)
@@ -103,6 +103,10 @@ const InfKronTravBandedBlockBandedLayout = LazyBandedMatricesInfiniteArraysExt.I
         @test bandwidths(view(A, Block(1, 1))) == (1, 1)
 
         @test A*A isa KronTrav
+        @test *(A,A,A) isa KronTrav
+        @test *(A,A,A,A) isa KronTrav
+        @test *(A,A,A,A,A) isa KronTrav
+        @test simplifiable(*,A,A) == Val(true)
         @test (A*A)[Block.(Base.OneTo(3)), Block.(Base.OneTo(3))] ≈ A[Block.(1:3), Block.(1:4)]A[Block.(1:4), Block.(1:3)]
 
         @testset "mul" begin