irrational sign() (#37949)

Author: Moelf

base/irrationals.jl

@@ -153,6 +153,8 @@ zero(::Type{<:AbstractIrrational}) = false
 one(::AbstractIrrational) = true
 one(::Type{<:AbstractIrrational}) = true
 
+sign(x::AbstractIrrational) = ifelse(x < zero(x), -1.0, 1.0)
+
 -(x::AbstractIrrational) = -Float64(x)
 for op in Symbol[:+, :-, :*, :/, :^]
     @eval $op(x::AbstractIrrational, y::AbstractIrrational) = $op(Float64(x),Float64(y))

test/numbers.jl

@@ -490,6 +490,8 @@ end
     @test isa(sign(2//3), Rational{Int})
     @test isa(2//3 + 2//3im, Complex{Rational{Int}})
     @test isa(sign(2//3 + 2//3im), ComplexF64)
+    @test sign(pi) === 1.0
+    @test sign(pi) === -sign(-pi)
     @test sign(one(UInt)) == 1
     @test sign(zero(UInt)) == 0