Make adjoint/transpose for Bidiagonal lazy

Author: jishnub

src/bidiag.jl

@@ -308,12 +308,12 @@ for func in (:conj, :copy, :real, :imag)
 end
 isreal(M::Bidiagonal) = isreal(M.dv) && isreal(M.ev)
 
-adjoint(B::Bidiagonal{<:Number}) = Bidiagonal(vec(adjoint(B.dv)), vec(adjoint(B.ev)), B.uplo == 'U' ? :L : :U)
-adjoint(B::Bidiagonal{<:Number, <:Base.ReshapedArray{<:Number,1,<:Adjoint}}) =
+adjoint(B::Bidiagonal) = Bidiagonal(vec(adjoint(B.dv)), vec(adjoint(B.ev)), B.uplo == 'U' ? :L : :U)
+adjoint(B::Bidiagonal{<:Any, <:Base.ReshapedArray{<:Any,1,<:AdjointAbsVec}}) =
     Bidiagonal(adjoint(parent(B.dv)), adjoint(parent(B.ev)), B.uplo == 'U' ? :L : :U)
-adjoint(B::Bidiagonal) = Bidiagonal(adjoint.(B.dv), adjoint.(B.ev), B.uplo == 'U' ? :L : :U)
-transpose(B::Bidiagonal{<:Number}) = Bidiagonal(B.dv, B.ev, B.uplo == 'U' ? :L : :U)
-transpose(B::Bidiagonal) = Bidiagonal(transpose.(B.dv), transpose.(B.ev), B.uplo == 'U' ? :L : :U)
+transpose(B::Bidiagonal) = Bidiagonal(vec(transpose(B.dv)), vec(transpose(B.ev)), B.uplo == 'U' ? :L : :U)
+transpose(B::Bidiagonal{<:Any, <:Base.ReshapedArray{<:Any,1,<:TransposeAbsVec}}) =
+    Bidiagonal(transpose(parent(B.dv)), transpose(parent(B.ev)), B.uplo == 'U' ? :L : :U)
 permutedims(B::Bidiagonal) = Bidiagonal(B.dv, B.ev, B.uplo == 'U' ? 'L' : 'U')
 function permutedims(B::Bidiagonal, perm)
     Base.checkdims_perm(axes(B), axes(B), perm)

test/bidiag.jl

@@ -1240,4 +1240,17 @@ end
     @test_throws BoundsError B[LinearAlgebra.BandIndex(0,size(B,1)+1)]
 end
 
+@testset "lazy adjtrans" begin
+    B = Bidiagonal(fill([1 2; 3 4], 3), fill([5 6; 7 8], 2), :U)
+    m = [2 4; 6 8]
+    for op in (transpose, adjoint)
+        C = op(B)
+        el = op(m)
+        C[1,1] = el
+        @test B[1,1] == m
+        C[2,1] = el
+        @test B[1,2] == m
+    end
+end
+
 end # module TestBidiagonal