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Use distinct types for RealInfinity #37

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Use distinct types for RealInfinity #37

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19c1091
Update Infinities.jl
putianyi889 Jun 6, 2023
cb8e5d9
remove obsolete codes
putianyi889 Jun 6, 2023
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40 changes: 20 additions & 20 deletions src/Infinities.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -107,15 +107,17 @@ function mod(x::Real, ::Infinity)
x
end

abstract type RealInfinity <: Real end
struct PositiveInfinity <: RealInfinity end
struct NegativeInfinity <: RealInfinity end
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Good, this also makes those two types into singleton types, which may allow for better code in a few places (avoiding allocations)


signbit(::PositiveInfinity) = false
signbit(::NegativeInfinity) = true

struct RealInfinity <: Real
signbit::Bool
end

RealInfinity() = RealInfinity(false)
RealInfinity(::Infinity) = RealInfinity()
RealInfinity() = PositiveInfinity()
RealInfinity(::Infinity) = PositiveInfinity()
RealInfinity(x::RealInfinity) = x
RealInfinity(x::Bool) = ifelse(x, NegativeInfinity(), PositiveInfinity())

-(::Infinity) = RealInfinity(true)
-(x::Number, ::Infinity) = x + (-∞)
Expand All @@ -127,7 +129,7 @@ RealInfinity(x::RealInfinity) = x
isinf(::RealInfinity) = true
isfinite(::RealInfinity) = false

promote_rule(::Type{Infinity}, ::Type{RealInfinity}) = RealInfinity
promote_rule(::Type{Infinity}, ::Type{<:RealInfinity}) = RealInfinity
_convert(::Type{RealInfinity}, ::Infinity) = RealInfinity(false)

_convert(::Type{Float16}, x::RealInfinity) = sign(x)*Inf16
Expand All @@ -136,8 +138,6 @@ _convert(::Type{Float64}, x::RealInfinity) = sign(x)*Inf64
_convert(::Type{T}, x::RealInfinity) where {T<:Real} = sign(x)*convert(T, Inf)
(::Type{T})(x::RealInfinity) where {T<:Real} = _convert(T, x)


signbit(y::RealInfinity) = y.signbit
sign(y::RealInfinity) = 1-2signbit(y)
angle(x::RealInfinity) = π*signbit(x)
mod(::RealInfinity, ::RealInfinity) = NotANumber()
Expand All @@ -150,9 +150,9 @@ end
string(y::RealInfinity) = signbit(y) ? "-∞" : "+∞"
show(io::IO, y::RealInfinity) = print(io, string(y))

==(x::RealInfinity, y::Infinity) = !x.signbit
==(y::Infinity, x::RealInfinity) = !x.signbit
==(x::RealInfinity, y::RealInfinity) = x.signbit == y.signbit
==(x::RealInfinity, y::Infinity) = !signbit(x)
==(y::Infinity, x::RealInfinity) = !signbit(x)
==(x::RealInfinity, y::RealInfinity) = signbit(x) == signbit(y)

==(x::RealInfinity, y::Number) = isinf(y) && signbit(y) == signbit(x)
==(y::Number, x::RealInfinity) = x == y
Expand Down Expand Up @@ -196,7 +196,7 @@ function -(x::RealInfinity, y::RealInfinity)
x
end

-(y::RealInfinity) = RealInfinity(!y.signbit)
-(y::RealInfinity) = RealInfinity(!signbit(y))

function +(x::RealInfinity, y::RealInfinity)
x == y || throw(ArgumentError("Angles must be the same to add ∞"))
Expand Down Expand Up @@ -231,12 +231,12 @@ for OP in (:<,:≤)
end


min(x::RealInfinity, y::RealInfinity) = RealInfinity(x.signbit | y.signbit)
max(x::RealInfinity, y::RealInfinity) = RealInfinity(x.signbit & y.signbit)
min(x::Real, y::RealInfinity) = y.signbit ? y : x
max(x::Real, y::RealInfinity) = y.signbit ? x : y
min(x::RealInfinity, y::Real) = x.signbit ? x : y
max(x::RealInfinity, y::Real) = x.signbit ? y : x
min(x::RealInfinity, y::RealInfinity) = RealInfinity(signbit(x) | signbit(y))
max(x::RealInfinity, y::RealInfinity) = RealInfinity(signbit(x) & signbit(y))
min(x::Real, y::RealInfinity) = signbit(y) ? y : x
max(x::Real, y::RealInfinity) = signbit(y) ? x : y
min(x::RealInfinity, y::Real) = signbit(x) ? x : y
max(x::RealInfinity, y::Real) = signbit(x) ? y : x
min(x::RealInfinity, ::Infinity) = x
max(::RealInfinity, ::Infinity) = ∞
min(::Infinity, x::RealInfinity) = x
Expand Down Expand Up @@ -275,7 +275,7 @@ isfinite(::ComplexInfinity) = false


promote_rule(::Type{Infinity}, ::Type{ComplexInfinity{T}}) where T = ComplexInfinity{T}
promote_rule(::Type{RealInfinity}, ::Type{ComplexInfinity{T}}) where T = ComplexInfinity{T}
promote_rule(::Type{<:RealInfinity}, ::Type{ComplexInfinity{T}}) where T = ComplexInfinity{T}
convert(::Type{ComplexInfinity{T}}, ::Infinity) where T = ComplexInfinity{T}()
convert(::Type{ComplexInfinity}, ::Infinity) = ComplexInfinity()
convert(::Type{ComplexInfinity{T}}, x::RealInfinity) where T = ComplexInfinity{T}(x)
Expand Down