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Define isnan for Number #38232

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Merged
merged 2 commits into from
Nov 4, 2020
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Define isnan for Number #38232

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f04ecdd
Define isnan for Number
bkamins Oct 29, 2020
4c68521
add test of <:Number
bkamins Oct 30, 2020
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2 changes: 1 addition & 1 deletion base/float.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -447,7 +447,7 @@ Test whether a number value is a NaN, an indeterminate value which is neither an
nor a finite number ("not a number").
"""
isnan(x::AbstractFloat) = (x != x)::Bool
isnan(x::Real) = false
isnan(x::Number) = false

isfinite(x::AbstractFloat) = x - x == 0
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@jw3126 jw3126 Oct 30, 2020

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How about isfinite? I think it is also not defined for Number?

Also a test would be good so this does not get deleted by accident.

struct N38232 <: Number end
@test isfinite(N38232())
@test !isnan(N38232())

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@bkamins bkamins Oct 30, 2020

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isfinite is not true by default. It is using Base.decompose for Real which is not exposed therefore I would leave the decision what to do it for a separate PR (fell free to open it; I need isnan for DataFrames.jl, as NaN has a special treatment in comparisons).

I will add the test you suggest - thank you.

isfinite(x::Real) = decompose(x)[3] != 0
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5 changes: 5 additions & 0 deletions test/floatfuncs.jl
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Expand Up @@ -178,3 +178,8 @@ end
@test ≈(1.0; atol=1).(1.0:3.0) == [true, true, false]

end

@testset "isnan for Number" begin
struct CustomNumber <: Number end
@test !isnan(CustomNumber())
end