Out-source n!/k! to Combinatorics.jl

JuliaAtoms · Jul 8, 2020 · 50387d5 · 50387d5
1 parent b92a18f
commit 50387d5
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Showing 5 changed files with 4 additions and 35 deletions.
diff --git a/Project.toml b/Project.toml
@@ -6,6 +6,7 @@ version = "0.1.0"
 [deps]
 AngularMomentumAlgebra = "0bb1b1ac-0216-11e9-361b-bb110c659ce1"
 AtomicLevels = "10933b4c-d60f-11e8-1fc6-bd9035a249a1"
+Combinatorics = "861a8166-3701-5b0c-9a16-15d98fcdc6aa"
 EnergyExpressions = "f4b57a2e-27c7-11e9-0cb0-edd185b706f6"
 HypergeometricFunctions = "34004b35-14d8-5ef3-9330-4cdb6864b03a"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
@@ -15,6 +16,7 @@ SpecialFunctions = "276daf66-3868-5448-9aa4-cd146d93841b"
 SpecialPolynomials = "a25cea48-d430-424a-8ee7-0d3ad3742e9e"
 
 [compat]
+Combinatorics = "1.0"
 HypergeometricFunctions = "0.2, 0.3"
 Polynomials = "1"
 SpecialFunctions = "0.10"

diff --git a/src/Hydrogen.jl b/src/Hydrogen.jl
@@ -2,6 +2,7 @@ module Hydrogen
 
 using LinearAlgebra
 using SparseArrays
+using Combinatorics
 
 using AtomicLevels
 using AngularMomentumAlgebra
@@ -13,7 +14,6 @@ using SpecialPolynomials: Laguerre
 using SpecialFunctions: gamma
 
 include("sparse_builder.jl")
-include("factorial_ratio.jl")
 
 include("constants.jl")
 include("energies.jl")

diff --git a/src/dipoles.jl b/src/dipoles.jl
@@ -50,7 +50,7 @@ function radial_dipole_moment(a::Orbital, b::Orbital)
     n == n′ && return 3/2*n*√(n^2-ℓ^2)
 
     A = powneg1(n′-ℓ)/(4*factorial(2ℓ-1))
-    B = √(factorial_ratio(n+ℓ,n-ℓ-1)*factorial_ratio(n′+ℓ-1,n′-ℓ))
+    B = √(factorial(n+ℓ,n-ℓ-1)*factorial(n′+ℓ-1,n′-ℓ))
     C = (4*n*n′)^(ℓ+1)*(n-n′)^(n+n′-2ℓ-2)/((n+n′)^(n+n′))
 
     nᵣ = n-ℓ-1

diff --git a/src/factorial_ratio.jl b/src/factorial_ratio.jl
diff --git a/test/runtests.jl b/test/runtests.jl
@@ -31,14 +31,6 @@ function lyman_balmer²(o, n, ℓ)
 end
 
 @testset "Hydrogen.jl" begin
-    @testset "Factorial ratios" begin
-        for a = 1:6
-            for b = 1:6
-                @test Hydrogen.factorial_ratio(a,b) == factorial(a)/factorial(b)
-            end
-        end
-    end
-
     @testset "Radial dipole moments" begin
         # We cannot compare with Table 13 of Bethe and Salpeter 1977,
         # since it provides so few figures and some of the values