tgorordo/WignerSymbols.jl
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Move halfinteger into WignerSymbols

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This commit is contained in:
Jutho Haegeman 2018-01-30 16:11:33 +08:00
parent 61eaa24215
commit ba3303cb68
2 changed files with 47 additions and 10 deletions
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src/halfinteger.jl Normal file
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# HalfInteger
struct HalfInteger <: Real
num::Int
end
Base.:+(a::HalfInteger, b::HalfInteger) = HalfInteger(a.num+b.num)
Base.:-(a::HalfInteger, b::HalfInteger) = HalfInteger(a.num-b.num)
Base.:-(a::HalfInteger) = HalfInteger(-a.num)
Base.:<=(a::HalfInteger, b::HalfInteger) = a.num <= b.num
Base.:<(a::HalfInteger, b::HalfInteger) = a.num < b.num
Base.one(::Type{HalfInteger}) = HalfInteger(2)
Base.zero(::Type{HalfInteger}) = HalfInteger(0)
Base.promote_rule(::Type{HalfInteger}, ::Type{<:Integer}) = HalfInteger
Base.promote_rule(::Type{HalfInteger}, T::Type{<:Rational}) = T
Base.promote_rule(::Type{HalfInteger}, T::Type{<:Real}) = T
Base.convert(::Type{HalfInteger}, n::Integer) = HalfInteger(2*n)
function Base.convert(::Type{HalfInteger}, r::Rational)
if r.den == 1
return HalfInteger(2*r.num)
elseif r.den == 2
return HalfInteger(r.num)
else
throw(InexactError())
end
end
Base.convert(::Type{HalfInteger}, r::Real) = convert(HalfInteger, convert(Rational, r))
Base.convert(T::Type{<:Real}, s::HalfInteger) = convert(T, s.num//2)
Base.convert(::Type{HalfInteger}, s::HalfInteger) = s
Base.isinteger(a::HalfInteger) = iseven(a.num)
ishalfinteger(a::HalfInteger) = true
ishalfinteger(a::Integer) = true
ishalfinteger(a::Rational) = a.den == 1 || a.den == 2
ishalfinteger(a::Real) = isinteger(2*a)
converthalfinteger(a::Number) = convert(HalfInteger, a)