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Fix incorrect sign of atanh(complex(x,y)) if x == -1 #31061

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Merged
merged 10 commits into from
Feb 19, 2019
Merged

Fix incorrect sign of atanh(complex(x,y)) if x == -1 #31061

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c445183
Fix incorrect sign in atanh
cafaxo Feb 13, 2019
d987fed
Formatting: Add space after comma
StefanKarpinski Feb 13, 2019
b30bf57
Add test
cafaxo Feb 13, 2019
a2f0998
Do not drop sign of zero
cafaxo Feb 14, 2019
2149a68
Flip sign to avoid a DomainError
cafaxo Feb 14, 2019
aa1c348
Test all four combinations
simonbyrne Feb 15, 2019
e3598fe
Tests for expressions that were signed incorrectly
cafaxo Feb 18, 2019
f8eacdb
Use the correct type for 1
cafaxo Feb 18, 2019
f9cef28
Update doc
cafaxo Feb 18, 2019
e4f0326
Update doc: Remove trailing whitespace
cafaxo Feb 18, 2019
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12 changes: 8 additions & 4 deletions base/complex.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -952,10 +952,14 @@ function atanh(z::Complex{T}) where T<:AbstractFloat
return Complex(copysign(zero(x),x), copysign(oftype(y,pi)/2, y))
end
return Complex(real(1/z), copysign(oftype(y,pi)/2, y))
elseif ax==1
end
β = copysign(one(T), x)
z *= β
x, y = reim(z)
if x == 1
if y == 0
ξ = copysign(oftype(x,Inf),x)
η = zero(y)
ξ = oftype(x, Inf)
η = y
else
ym = ay+ρ
ξ = log(sqrt(sqrt(4+y*y))/sqrt(ym))
Expand All @@ -970,7 +974,7 @@ function atanh(z::Complex{T}) where T<:AbstractFloat
end
η = angle(Complex((1-x)*(1+x)-ysq, 2y))/2
end
Complex(ξ, η)
β * Complex(ξ, η)
end
atanh(z::Complex) = atanh(float(z))

Expand Down
4 changes: 2 additions & 2 deletions stdlib/LinearAlgebra/src/dense.jl
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Expand Up @@ -926,8 +926,8 @@ this function, see [^AH16_1].
```jldoctest
julia> acos(cos([0.5 0.1; -0.2 0.3]))
2×2 Array{Complex{Float64},2}:
0.5-5.55112e-17im 0.1-2.77556e-17im
-0.2+2.498e-16im 0.3-3.46945e-16im
0.5-8.32667e-17im 0.1+0.0im
-0.2+2.63678e-16im 0.3-3.46945e-16im
```
"""
function acos(A::AbstractMatrix)
Expand Down
9 changes: 9 additions & 0 deletions test/complex.jl
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Expand Up @@ -696,7 +696,9 @@ end
@test isequal(atanh(complex(-0.0,-Inf)),complex(-0.0,-pi/2))

@test isequal(atanh(complex( 1.0, 0.0)),complex( Inf, 0.0))
@test isequal(atanh(complex( 1.0,-0.0)),complex( Inf,-0.0))
@test isequal(atanh(complex(-1.0, 0.0)),complex(-Inf, 0.0))
@test isequal(atanh(complex(-1.0,-0.0)),complex(-Inf,-0.0))
@test isequal(atanh(complex( 5.0, Inf)),complex( 0.0, pi/2))
@test isequal(atanh(complex( 5.0,-Inf)),complex( 0.0,-pi/2))
@test isequal(atanh(complex( 5.0, NaN)),complex( NaN, NaN))
Expand Down Expand Up @@ -1065,3 +1067,10 @@ end

@test @inferred(2.0^(3.0+0im)) === @inferred((2.0+0im)^(3.0+0im)) === @inferred((2.0+0im)^3.0) === 8.0+0.0im
end

@testset "issue #31054" begin
@test tanh(atanh(complex(1.0,1.0))) == complex(1.0,1.0)
@test tanh(atanh(complex(1.0,-1.0))) == complex(1.0,-1.0)
@test tanh(atanh(complex(-1.0,1.0))) == complex(-1.0,1.0)
@test tanh(atanh(complex(-1.0,-1.0))) == complex(-1.0,-1.0)
end