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Pass through nothing strides #1610

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b9da9dc
pass through `nothing` strides
nhz2 May 18, 2026
b4af62a
define strides on transpose with Number eltype
nhz2 May 18, 2026
2ce35a1
Merge branch 'master' into nz/fix-strides
nhz2 May 18, 2026
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24 changes: 20 additions & 4 deletions src/adjtrans.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -368,11 +368,27 @@ convert(::Type{Adjoint{T,S}}, A::Adjoint) where {T,S} = Adjoint{T,S}(convert(S,
convert(::Type{Transpose{T,S}}, A::Transpose) where {T,S} = Transpose{T,S}(convert(S, A.parent))::Transpose{T,S}

# Strides and pointer for transposed strided arrays — but only if the elements are actually stored in memory
Base.strides(A::Adjoint{<:Real, <:AbstractVector}) = (stride(A.parent, 2), stride(A.parent, 1))
Base.strides(A::Transpose{<:Any, <:AbstractVector}) = (stride(A.parent, 2), stride(A.parent, 1))
function Base.strides(A::Adjoint{<:Real, <:AbstractVector})
st = strides(A.parent)
isnothing(st) && return nothing
(st[1]*Int(length(A.parent)), st[1])

@nhz2 nhz2 May 18, 2026

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st[1]*Int(length(A.parent)) should match stride(A.parent, 2) since the parent is an abstract vector: https://github.com/JuliaLang/julia/blob/201e056e9ee2398f01ecd2f104f9d8000b04d195/base/abstractarray.jl#L602

JuliaLang/julia#30432 has this return (1, st[1]). The first stride should not get used, so in theory its value shouldn't matter.

end
function Base.strides(A::Transpose{<:Number, <:AbstractVector})
st = strides(A.parent)
isnothing(st) && return nothing
(st[1]*Int(length(A.parent)), st[1])
end
# For matrices it's slightly faster to use reverse and avoid calling stride twice
Base.strides(A::Adjoint{<:Real, <:AbstractMatrix}) = reverse(strides(A.parent))
Base.strides(A::Transpose{<:Any, <:AbstractMatrix}) = reverse(strides(A.parent))
function Base.strides(A::Adjoint{<:Real, <:AbstractMatrix})
st = strides(A.parent)
isnothing(st) && return nothing
reverse(st)
end
function Base.strides(A::Transpose{<:Number, <:AbstractMatrix})
st = strides(A.parent)
isnothing(st) && return nothing
reverse(st)
end

Base.cconvert(::Type{Ptr{T}}, A::Adjoint{<:Real, <:AbstractVecOrMat}) where {T} = Base.cconvert(Ptr{T}, A.parent)
Base.cconvert(::Type{Ptr{T}}, A::Transpose{<:Any, <:AbstractVecOrMat}) where {T} = Base.cconvert(Ptr{T}, A.parent)
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12 changes: 10 additions & 2 deletions test/adjtrans.jl
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Expand Up @@ -571,6 +571,14 @@ end
@test repr(transpose([1f0,2f0])) == "transpose(Float32[1.0, 2.0])"
end

function test_no_strides(x)
@test try
strides(x)
catch e
e
end isa Union{MethodError, Nothing}
end

@testset "strided transposes" begin
for t in (Adjoint, Transpose)
@test strides(t(rand(3))) == (3, 1)
Expand All @@ -583,8 +591,8 @@ end
B = rand(3,1)
@test pointer(t(B)) === pointer(B)
end
@test_throws MethodError strides(Adjoint(rand(3) .+ rand(3).*im))
@test_throws MethodError strides(Adjoint(rand(3, 2) .+ rand(3, 2).*im))
test_no_strides(Adjoint(rand(3) .+ rand(3).*im))
test_no_strides(Adjoint(rand(3, 2) .+ rand(3, 2).*im))
@test strides(Transpose(rand(3) .+ rand(3).*im)) == (3, 1)
@test strides(Transpose(rand(3, 2) .+ rand(3, 2).*im)) == (3, 1)

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20 changes: 13 additions & 7 deletions test/blas.jl
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Expand Up @@ -598,6 +598,14 @@ Base.cconvert(::Type{Ptr{T}}, A::WrappedArray{T}) where T = Base.cconvert(Ptr{T}
Base.strides(A::WrappedArray) = strides(A.A)
Base.elsize(::Type{WrappedArray{T,N}}) where {T,N} = Base.elsize(Array{T,N})

function test_no_strides(x)
@test try
strides(x)
catch e
e
end isa Union{MethodError, Nothing}
end

@testset "strided interface adjtrans" begin
x = WrappedArray([1, 2, 3, 4])
@test stride(x,1) == 1
Expand All @@ -617,20 +625,18 @@ Base.elsize(::Type{WrappedArray{T,N}}) where {T,N} = Base.elsize(Array{T,N})
y = WrappedArray([1+im, 2, 3, 4])
@test strides(transpose(y)) == (4,1)
@test pointer(transpose(y)) == pointer(y)
@test_throws MethodError strides(y')
test_no_strides(y')
@test_throws ErrorException pointer(y')

B = WrappedArray([1+im 2; 3 4; 5 6])
@test strides(transpose(B)) == (3,1)
@test pointer(transpose(B)) == pointer(B)
@test_throws MethodError strides(B')
test_no_strides(B')
@test_throws ErrorException pointer(B')

@test_throws MethodError stride(1:5,0)
@test_throws MethodError stride(1:5,1)
@test_throws MethodError stride(1:5,2)
@test_throws MethodError strides(transpose(1:5))
@test_throws MethodError strides((1:5)')
test_no_strides(1:5)
test_no_strides(transpose(1:5))
test_no_strides((1:5)')
@test_throws ErrorException pointer(transpose(1:5))
@test_throws ErrorException pointer((1:5)')
end
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