Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

fix invpow and invlog domains #23

Merged
merged 5 commits into from
Sep 26, 2022
Merged

fix invpow and invlog domains #23

Show file tree
Hide file tree
Changes from 4 commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
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
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
41 changes: 36 additions & 5 deletions src/functions.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -12,13 +12,44 @@ function square(x::Real)
end


invpow2(x::Real, p::Integer) = sign(x) * abs(x)^inv(p)
invpow2(x::Real, p::Real) = x ≥ zero(x) ? x^inv(p) : throw(DomainError(x, "inverse for x^$p is not defined at $x"))
invpow2(x, p) = x^inv(p)
function invpow2(x::Real, p::Integer)
if x ≥ zero(x) || isodd(p)
copysign(abs(x)^inv(p), x)
else
throw(DomainError(x, "inverse for x^$p is not defined at $x"))
end
end
function invpow2(x::Real, p::Real)
if x ≥ zero(x)
x^inv(p)
else
throw(DomainError(x, "inverse for x^$p is not defined at $x"))
end
end
function invpow2(x, p::Real)
# complex x^p is only invertible for p = 1/n
if isinteger(inv(p))
x^inv(p)
else
throw(DomainError(x, "inverse for x^$p is not defined at $x"))
end
end

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

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 $x"))
function invlog1(b::Real, x::Real)
if b ≥ zero(b)
b^x
else
throw(DomainError(x, "inverse for log($b, x) is not defined at $x"))
aplavin marked this conversation as resolved.
Show resolved Hide resolved
end
end
invlog1(b, x) = b^x

invlog2(b, x) = x^inv(b)
11 changes: 8 additions & 3 deletions test/test_inverse.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
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, rand()), Base.Fix1(log, 1/rand()), Base.Fix2(log, rand()),
)
InverseFunctions.test_inverse(f, x)
end
Expand All @@ -56,9 +56,14 @@ 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)
InverseFunctions.test_inverse(inverse(Base.Fix1(log, 2)), complex(-5))
@test_throws DomainError inverse(Base.Fix2(^, 0.5))(-5)
InverseFunctions.test_inverse(Base.Fix2(^, 0.5), -5 + 0im)
@test_throws DomainError inverse(Base.Fix2(^, 0.51))(complex(-5))
InverseFunctions.test_inverse(Base.Fix2(^, 0.5), complex(-5))
@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_throws DomainError inverse(Base.Fix1(^, -2))(3)

A = rand(5, 5)
for f in (
Expand Down