Tridiagonal qr

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "InfiniteLinearAlgebra"
 uuid = "cde9dba0-b1de-11e9-2c62-0bab9446c55c"
-version = "0.5.1"
+version = "0.5.2"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/InfiniteLinearAlgebra.jl

@@ -9,7 +9,7 @@ import Base.Broadcast: BroadcastStyle, Broadcasted, broadcasted
 
 import ArrayLayouts: colsupport, rowsupport, triangularlayout, MatLdivVec, triangulardata, TriangularLayout, TridiagonalLayout, 
                         sublayout, _qr, __qr, MatLmulVec, MatLmulMat, AbstractQLayout, materialize!, diagonaldata, subdiagonaldata, supdiagonaldata,
-                        _bidiag_forwardsub!, mulreduce, RangeCumsum
+                        _bidiag_forwardsub!, mulreduce, RangeCumsum, _factorize
 import BandedMatrices: BandedMatrix, _BandedMatrix, AbstractBandedMatrix, bandeddata, bandwidths, BandedColumns, bandedcolumns,
                         _default_banded_broadcast, banded_similar
 import FillArrays: AbstractFill, getindex_value, axes_print_matrix_row

src/infqr.jl

@@ -151,6 +151,7 @@ _qr(::AbstractBandedLayout, ::NTuple{2,OneToInf{Int}}, A) = adaptiveqr(A)
 _qr(::AbstractAlmostBandedLayout, ::NTuple{2,OneToInf{Int}}, A) = adaptiveqr(A)
 __qr(_, ::NTuple{2,InfiniteCardinal{0}}, A) = adaptiveqr(A)
 _qr(::AbstractBlockBandedLayout, ::NTuple{2,InfiniteCardinal{0}}, A) = adaptiveqr(A)
+_factorize(::AbstractBandedLayout, ::NTuple{2,OneToInf{Int}}, A) = qr(A)
 
 partialqr!(F::QR, n) = partialqr!(F.factors, n)
 partialqr!(F::AdaptiveQRFactors, n) = partialqr!(F.data, n)

test/test_infqr.jl

@@ -100,6 +100,12 @@ import SemiseparableMatrices: AlmostBandedLayout, VcatAlmostBandedLayout
             A = BandedMatrix(0 => -2*(0:∞)/z, 1 => Ones(∞), -1 => Ones(∞))
             @time J = A \ Vcat([besselj(1,z)], Zeros(∞))
             @test J[1:20_000] ≈ [besselj(k,z) for k=0:20_000-1]
+
+            # Tridiagonal works too
+            A =  LazyBandedMatrices.Tridiagonal(Ones(∞), -2*(0:∞)/z, Ones(∞))
+            @test factorize(A) isa MatrixFactorizations.QR
+            @time J = A \ [besselj(1,z); Zeros(∞)]
+            @test J[1:20_000] ≈ [besselj(k,z) for k=0:20_000-1]
         end
 
         @testset "5-band" begin