Special case blockbandwidths for unitblocks (#207)

* Special case for unitblocks

* Update test_misc.jl

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "BlockBandedMatrices"
 uuid = "ffab5731-97b5-5995-9138-79e8c1846df0"
-version = "0.13"
+version = "0.13.1"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/interfaceimpl.jl

@@ -73,3 +73,11 @@ _blockkron(::Tuple{Vararg{AbstractBandedLayout}}, A) = BandedBlockBandedMatrix(B
 
 
 sublayout(::DiagonalLayout{L}, inds::Type{<:NTuple{2,BS}}) where {L,BS<:BlockSlice{<:BlockRange1}} = bandedblockbandedcolumns(sublayout(L(),Tuple{BS}))
+
+
+
+##
+# special for unitblocks
+blockbandwidths(A::BlockedMatrix{<:Any,<:Any,<:NTuple{2,BlockedOneTo{Int,<:AbstractUnitRange{Int}}}}) = bandwidths(A.blocks)
+blockbandwidths(A::BlockedMatrix{<:Any,<:Diagonal,<:NTuple{2,BlockedOneTo{Int,<:AbstractUnitRange{Int}}}}) = bandwidths(A.blocks)
+subblockbandwidths(A::BlockedMatrix{<:Any,<:Any,<:NTuple{2,BlockedOneTo{Int,<:AbstractUnitRange{Int}}}}) = (0,0)

test/test_misc.jl

@@ -247,6 +247,15 @@ Base.size(F::FiniteDifference) = (F.n,F.n)
 
         @test BandedBlockBandedMatrix(D̃_yy) ≈ D_yy
     end
+
+    @testset "banded with unitblocks" begin
+        A = BlockedArray(brand(5,4,1,2), Ones{Int}(5), Ones{Int}(4))
+        @test bandwidths(A) == blockbandwidths(A) == (1,2)
+        @test subblockbandwidths(A) == (0,0)
+        D = BlockedArray(Diagonal(1:5), Ones{Int}(5), Ones{Int}(5))
+        @test bandwidths(D) == blockbandwidths(D) == (0,0)
+        @test subblockbandwidths(D) == (0,0)
+    end
 end
 
 end # module