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Iterator norm in isapprox for Arrays #1378

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4abc6fe
Iterator norm in `isapprox` for `Array`s
jishnub Jun 4, 2025
abfb65d
Handle empty arrays
jishnub Jun 4, 2025
4906add
Specialize for strided contiguous `SubArray`s
jishnub Jun 13, 2025
2a7518e
Limit to Array views
jishnub Jun 20, 2025
35c5dd3
Remove initial call before `@allocated` test
jishnub Jun 20, 2025
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14 changes: 13 additions & 1 deletion src/generic.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -2004,7 +2004,12 @@ function isapprox(x::AbstractArray, y::AbstractArray;
atol::Real=0,
rtol::Real=Base.rtoldefault(promote_leaf_eltypes(x),promote_leaf_eltypes(y),atol),
nans::Bool=false, norm::Function=norm)
d = norm(x - y)
Base.promote_shape(size(x), size(y)) # ensure compatible size
d = if isempty(x) && isempty(y)
norm(zero(eltype(x)) - zero(eltype(y)))
else
norm_x_minus_y(x, y)
end
if isfinite(d)
return iszero(rtol) ? d <= atol : d <= max(atol, rtol*max(norm(x), norm(y)))
else
Expand All @@ -2014,6 +2019,13 @@ function isapprox(x::AbstractArray, y::AbstractArray;
end
end

norm_x_minus_y(x, y) = norm(x - y)
FastContiguousArrayView{T,N,P<:Array,I<:Tuple{AbstractUnitRange, Vararg{Any}}} = Base.SubArray{T,N,P,I,true}
const ArrayOrFastContiguousArrayView = Union{Array, FastContiguousArrayView}
function norm_x_minus_y(x::ArrayOrFastContiguousArrayView, y::ArrayOrFastContiguousArrayView)
norm(Iterators.map(splat(-), zip(x,y)))
end

"""
normalize!(a::AbstractArray, p::Real=2)

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7 changes: 7 additions & 0 deletions test/generic.jl
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Expand Up @@ -938,4 +938,11 @@ end
@test B == A2
end

@testset "isapprox for Arrays" begin
A = rand(3,3)
n = @allocated isapprox(A, A)
@test n == 0
@test Int[] ≈ Int[]
end

end # module TestGeneric