This commit is contained in:
Jutho Haegeman 2017-08-09 12:13:46 +02:00
parent 46d5624e0f
commit b9eb46d5cd
2 changed files with 93 additions and 58 deletions

View file

@ -1,9 +1,9 @@
module WignerSymbols
export wigner3j, wigner6j
export δ, Δ, clebschgordan, wigner3j, wigner6j
include("primefactorization.jl")
const Wigner3j = Dict{NTuple{5,UInt},Tuple{Rational{BigInt},Rational{BigInt}}}()
const Wigner3j = Dict{Tuple{UInt,UInt,UInt,Int,Int},Tuple{Rational{BigInt},Rational{BigInt}}}()
const Wigner6j = Dict{NTuple{6,UInt},Tuple{Rational{BigInt},Rational{BigInt}}}()
clebschgordan(j₁, m₁, j₂, m₂, j₃, m₃ = m₁+m₂) = clebschgordan(Float64, j₁, m₁, j₂, m₂, j₃, m₃)
@ -21,19 +21,35 @@ wigner3j(j₁, j₂, j₃, m₁, m₂, m₃ = -m₂-m₃) = wigner3j(Float64, j
function wigner3j(T::Type{<:AbstractFloat}, j₁, j₂, j₃, m₁, m₂, m₃ = -m₂-m₃)
# check angular momenta and triangle condition
if !(δ(j₁, j₂, j₃) && ϵ(j₁, m₁) && ϵ(j₂, m₂) && ϵ(j₃, m₃))
throw(DomainError())
throw(DomainError((j₁, j₂, j₃, m₁, m₂, m₃)))
end
iszero(m₁+m₂+m₃) || return zero(T)
# we reorder such that j₁ >= j₂ >= j₃ and m₁ >= 0 or m₁ == 0 && m₂ >= 0
j₁, j₂, j₃, m₁, m₂, m₃, sgn = reorder3j(j₁, j₂, j₃, m₁, m₂, m₃)
# do we also want to use Regge symmetries?
α₁ = convert(Int, j₂ - m₁ - j₃ ) # can be negative
α₂ = convert(Int, j₁ + m₂ - j₃ ) # can be negative
β₁ = convert(Int, j₁ + j₂ - j₃ )
β₂ = convert(Int, j₁ - m₁ )
β₃ = convert(Int, j₂ + m₂ )
# extra sign in definition
sgn = isodd(j₁ - j₃ - m₃) ? -sgn : sgn
# dictionary lookup or compute
if haskey(Wigner3j, (j₁, j₂, j₃, m₁, m₂))
r, s = Wigner3j[(j₁, j₂, j₃, m₁, m₂)]
if haskey(Wigner3j, (β₁, β₂, β₃, α₁, α))
r, s = Wigner3j[(β₁, β₂, β₃, α₁, α)]
else
r, s = compute3j(j₁, j₂, j₃, m₁, m₂)
Wigner3j[(j₁, j₂, j₃, m₁, m₂)] = (r,s)
s1 = Δ²(j₁, j₂, j₃)
s2 = prod(map(primefactorial, (β₂, β₁ - α₁, β₁ - α₂, β₃, β₃ - α₁, β₂ - α₂)))
snum, rnum = splitsquare(s1.num * s2)
sden, rden = splitsquare(s1.den)
s = convert(BigInt, snum) // convert(BigInt, sden)
r = convert(BigInt, rnum) // convert(BigInt, rden)
s *= compute3jseries(β₁, β₂, β₃, α₁, α₂)
Wigner3j[(β₁, β₂, β₃, α₁, α₂)] = (r,s)
end
return sgn*sqrt(convert(T, r))*convert(T, s)
@ -48,7 +64,8 @@ function wigner6j(T::Type{<:AbstractFloat}, j₁, j₂, j₃, j₄, j₅, j₆)
# check triangle conditions
if !(δ(α̂₁...) && δ(α̂₂...) && δ(α̂₃...) && δ(α̂₄...))
throw(DomainError())
return zero(T)
# throw(DomainError())
end
# reduce
α₁ = convert(UInt, +(α̂₁...))
@ -100,6 +117,15 @@ function δ(j₁, j₂, j₃)
return true
end
# triangle coefficient
function Δ(T::Type{<:AbstractFloat}, j₁, j₂, j₃)
if !δ(j₁, j₂, j₃)
throw(DomainError())
end
v = Δ²(j₁, j₂, j₃)
return sqrt(convert(T, convert(BigInt, v.num) // convert(BigInt, v.den)))
end
# squared triangle coefficient
function Δ²(j₁, j₂, j₃)
# also checks the triangle conditions by converting to unsigned integer:
@ -113,11 +139,11 @@ end
# reorder parameters determining the 3j symbol to canonical order:
# j₁ >= j₂ >= j₃ and m₁ >= 0 or m₁ == 0 && m₂ >= 0
function reorder3j(j₁, j₂, j₃, m₁, m₂, m₃, sgn = one(UInt8))
function reorder3j(j₁, j₂, j₃, m₁, m₂, m₃, sign = one(UInt8))
if j₁ < j₂
return reorder3j(j₂, j₁, j₃, m, m₂, m₃, -sign)
return reorder3j(j₂, j₁, j₃, m, m₁, m₃, -sign)
elseif j₂ < j₃
return reorder3j(j₁, j₃, j₂, m₁, m, m₃, -sign)
return reorder3j(j₁, j₃, j₂, m₁, m, m₂, -sign)
elseif m₁ < zero(m₁)
return reorder3j(j₁, j₂, j₃, -m₁, -m₂, -m₃, -sign)
elseif iszero(m₁) && m₂ < zero(m₂)
@ -149,37 +175,42 @@ function reorder6j(β₁, β₂, β₃, α₁, α₂, α₃, α₄)
end
end
function compute3j(j₁, j₂, j₃, m₁, m₂)
m₃ = -m₁ - m₂
α₁ = convert(UInt, j₂ - m₁ - j₃ )
α₂ = convert(UInt, j₁ + m₂ - j₃ )
β₁ = convert(UInt, j₁ + j₂ - j₃ )
β₂ = convert(UInt, j₁ - m₁ )
β₃ = convert(UInt, j₂ + m₂ )
krange = max(α₁,α₂,zero(UInt)):min(β₁,β₂,β₃)
end
# compute the sum appearing in the 6j symbol
function compute6jseries(β₁, β₂, β₃, α₁, α₂, α₃, α₄)
krange = max(α₁,α₂,α₃,α₄):min(β₁,β₂,β₃)
nums = Vector{typeof(snum)}(length(krange))
dens = Vector{typeof(snum)}(length(krange))
# compute the sum appearing in the 3j symbol
function compute3jseries(β₁, β₂, β₃, α₁, α₂)
krange = max(α₁, α₂, zero(α₁)):min(β₁, β₂, β₃)
T = PrimeFactorization{eltype(eltype(factorialtable))}
nums = Vector{T}(length(krange))
dens = Vector{T}(length(krange))
for (i, k) in enumerate(krange)
num = iseven(k) ? primefactorial(k+1) : -primefactorial(k+1)
den = primefactorial(k-α₁)*primefactorial(k-α₂)*primefactorial(k-α₃)*
primefactorial(k-α₄)*primefactorial(β₁-k)*primefactorial(β₂-k)*primefactorial(β₃-k)
nums[i], dens[i] = divgcd(num, den)
num = iseven(k) ? primefactorial(1) : -primefactorial(1)
den = primefactorial(k)*primefactorial(k-α₁)*primefactorial(k-α₂)*
primefactorial(β₁-k)*primefactorial(β₂-k)*primefactorial(β₃-k)
nums[i], dens[i] = divgcd!(num, den)
end
den = commondenominator!(nums, dens)
totalnum = sumlist!(nums)
totalden = convert(BigInt, PrimeFactorization(den))
return totalnum//totalden
end
# compute the sum appearing in the 6j symbol
function compute6jseries(β₁, β₂, β₃, α₁, α₂, α₃, α₄)
krange = max(α₁, α₂, α₃, α₄):min(β₁, β₂, β₃)
T = PrimeFactorization{eltype(eltype(factorialtable))}
nums = Vector{T}(length(krange))
dens = Vector{T}(length(krange))
for (i, k) in enumerate(krange)
num = iseven(k) ? primefactorial(k+1) : -primefactorial(k+1)
den = primefactorial(k-α₁)*primefactorial(k-α₂)*primefactorial(k-α₃)*
primefactorial(k-α₄)*primefactorial(β₁-k)*primefactorial(β₂-k)*primefactorial(β₃-k)
nums[i], dens[i] = divgcd!(num, den)
end
den = commondenominator!(nums, dens)
totalnum = sumlist!(nums)
totalden = convert(BigInt, PrimeFactorization(den))
return totalnum//totalden
end
end # module

View file

@ -57,6 +57,7 @@ end
PrimeFactorization(powers::Vector{T}) where {T<:Unsigned} = PrimeFactorization{T}(powers, one(Int8))
Base.copy(a::PrimeFactorization) = PrimeFactorization(copy(a.powers), a.sign)
Base.:(==)(a::P, b::P) where {P<:PrimeFactorization} = a.powers == b.powers && a.sign == b.sign
# define our own factor function, returning an instance of PrimeFactorization
function primefactor(n::Integer)
@ -81,11 +82,11 @@ function primefactor(n::Integer)
end
push!(factortable, powers)
end
@inbounds return PrimeFactorization(factortable[n], sn)
@inbounds return PrimeFactorization(copy(factortable[n]), sn)
end
function primefactorial(n::Integer)
n < 0 && return DomainError(n)
n < 0 && throw(DomainError(n))
m = length(factorialtable)-1
@inbounds while m < n
prevfactorial = factorialtable[m+1]
@ -100,7 +101,7 @@ function primefactorial(n::Integer)
end
push!(factorialtable, powers)
end
@inbounds return PrimeFactorization(factorialtable[n+1])
@inbounds return PrimeFactorization(copy(factorialtable[n+1]))
end
# Conversion from PrimeFactorization to `BigInt` using `bigprime`
@ -134,7 +135,7 @@ function Base.gcd(a::PrimeFactorization{T}, b::PrimeFactorization{T}) where {T}
elseif b.sign ==0
return a
else
return Primefactorization(_vmin!(copy(a.powers), b.powers))
return PrimeFactorization(_vmin!(copy(a.powers), b.powers))
end
end
function Base.lcm(a::PrimeFactorization{T}, b::PrimeFactorization{T}) where {T}
@ -143,33 +144,37 @@ function Base.lcm(a::PrimeFactorization{T}, b::PrimeFactorization{T}) where {T}
elseif b.sign ==0
return b
else
return Primefactorization(_vmax!(copy(a.powers), b.powers))
return PrimeFactorization(_vmax!(copy(a.powers), b.powers))
end
end
function Base.divgcd(a::PrimeFactorization{T}, b::PrimeFactorization{T}) where {T}
Base.divgcd(a::PrimeFactorization{T}, b::PrimeFactorization{T}) where {T} = divgcd!(copy(a), copy(b))
function divgcd!(a::PrimeFactorization{T}, b::PrimeFactorization{T}) where {T}
af, bf = a.powers, b.powers
ag = copy(af)
bg = copy(bf)
for k = 1:min(length(ag), length(bg))
gk = min(ag[k], bg[k])
ag[k] -= gk
bg[k] -= gk
for k = 1:min(length(af), length(bf))
gk = min(af[k], bf[k])
af[k] -= gk
bf[k] -= gk
end
while length(ag) > 0 && iszero(last(ag))
pop!(ag)
while length(af) > 0 && iszero(last(af))
pop!(af)
end
while length(bg) > 0 && iszero(last(bg))
pop!(bg)
while length(bf) > 0 && iszero(last(bf))
pop!(bf)
end
return PrimeFactorization{T}(ag, a.sign), PrimeFactorization{T}(bg, b.sign)
return a, b
end
# split `a::PrimeFactorization` into a square `s` and a remainder `r`, such that
# `a = s^2 * r` and the powers in the prime factorization of `r` are zero or one
function splitsquare(a::PrimeFactorization)
r = PrimeFactorization(map(p->convert(UInt8, isodd(p)), a.powers), a.sign)
while length(r.powers) > 0 && iszero(last(r.powers))
pop!(r.powers)
end
s = PrimeFactorization(map(p->(p>>1), a.powers))
while length(s.powers) > 0 && iszero(last(s.powers))
pop!(s.powers)
end
return s, r
end
@ -191,8 +196,8 @@ end
# auxiliary function to compute sums of a list of PrimeFactorizations as quickly as possible
function sumlist!(list::Vector{<:PrimeFactorization}, ind = 1:length(list))
# depending on length, sum smaller parts first
g = copy(list[ind[1]])
# first compute gcd to take out common factors
g = PrimeFactorization(copy(list[ind[1]].powers))
for k in ind
_vmin!(g.powers, list[k].powers)
end
@ -204,8 +209,7 @@ function sumlist!(list::Vector{<:PrimeFactorization}, ind = 1:length(list))
l = L >> 1
s = sumlist!(list, first(ind)+(0:l-1)) + sumlist!(list, first(ind)+(l:L-1))
else
# first compute gcd to take out common factors
# do sum
s = big(0)
for k in ind
Base.GMP.MPZ.add!(s, convert(BigInt, list[k]))