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fix invpow and invlog domains #23

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merged 5 commits into from
Sep 26, 2022
Merged

fix invpow and invlog domains #23

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283630a
fix invpow domains
aplavin Aug 17, 2022
3e9216b
fix invlog domain
aplavin Aug 17, 2022
283fc06
after review comments
aplavin Sep 13, 2022
f6863b1
after review 2
aplavin Sep 25, 2022
42139b3
fix coverage
aplavin Sep 26, 2022
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7 changes: 3 additions & 4 deletions src/functions.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -12,13 +12,12 @@ function square(x::Real)
end


invpow2(x::Real, p::Integer) = sign(x) * abs(x)^inv(p)
invpow2(x::Real, p::Integer) = x ≥ zero(x) || isodd(p) ? sign(x) * abs(x)^inv(p) : throw(DomainError(x, "inverse for x^$p is not defined at $x"))
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invpow2(x::Real, p::Real) = x ≥ zero(x) ? x^inv(p) : throw(DomainError(x, "inverse for x^$p is not defined at $x"))
invpow2(x, p) = x^inv(p)

invpow1(b, x) = log(abs(b), abs(x))
invpow1(b::Real, x::Real) = b ≥ zero(b) && x ≥ zero(x) ? log(b, x) : throw(DomainError(x, "inverse for $b^x is not defined at $x"))
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invlog1(b::Real, x::Real) = b ≥ zero(b) && x ≥ zero(x) ? b^x : throw(DomainError(x, "inverse for log($b, x) is not defined at $x"))
invlog1(b::Real, x::Real) = b ≥ zero(b) ? b^x : throw(DomainError(x, "inverse for log($b, x) is not defined at $x"))
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invlog1(b, x) = b^x

invlog2(b, x) = x^inv(b)
9 changes: 6 additions & 3 deletions test/test_inverse.jl
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Expand Up @@ -37,7 +37,7 @@ InverseFunctions.inverse(f::Bar) = Bar(inv(f.A))
x = rand()
for f in (
foo, inv_foo, log, log2, log10, log1p, sqrt,
Base.Fix2(^, rand()), Base.Fix2(^, rand([-10:-1; 1:10])), Base.Fix1(^, rand()), Base.Fix1(log, rand()), Base.Fix2(log, rand()),
Base.Fix2(^, rand()), Base.Fix2(^, rand([-10:-1; 1:10])), Base.Fix1(^, rand()), Base.Fix1(log, 5rand()), Base.Fix2(log, rand()),
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)
InverseFunctions.test_inverse(f, x)
end
Expand All @@ -56,9 +56,12 @@ InverseFunctions.inverse(f::Bar) = Bar(inv(f.A))
@test_throws DomainError inverse(Base.Fix1(*, 0))
@test_throws DomainError inverse(Base.Fix2(^, 0))
@test_throws DomainError inverse(Base.Fix1(log, 2))(-5)
InverseFunctions.test_inverse(Base.Fix1(log, 2), -5 + 0im)
@test inverse(Base.Fix1(log, 2))(-5 + 0im) == 0.03125 + 0im
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@test_throws DomainError inverse(Base.Fix2(^, 0.5))(-5)
InverseFunctions.test_inverse(Base.Fix2(^, 0.5), -5 + 0im)
@test_throws DomainError inverse(Base.Fix2(^, 2))(-5)
@test_throws DomainError inverse(Base.Fix1(^, 2))(-5)
@test_throws DomainError inverse(Base.Fix1(^, -2))(3)
@test inverse(Base.Fix1(^, 2))(0) == -Inf
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A = rand(5, 5)
for f in (
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