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Refactor factorial function #35

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Merged
Expander merged 3 commits into from
Apr 20, 2025
Merged

Refactor factorial function #35

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8653eb6
use generic conversion to appropriate floating point
Expander Apr 20, 2025
68f0ec6
merge factorial functions
Expander Apr 20, 2025
30c8094
refactor inv_fac
Expander Apr 20, 2025
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52 changes: 14 additions & 38 deletions src/Factorial.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -122,54 +122,30 @@ const INVERSE_FACTORIALS = (

# returns n! for n >= 0
function fac(n::Integer, ::Type{T})::T where T
if issimplefloat(T)
convert(T, fac_f64(n))
else
fac_big(n)
end
end

function fac_f64(n::Integer)::Float64
if n < 0
throw(DomainError(n, "fac not implemented for n < 0"))
elseif n + 1 <= length(FACTORIALS)
FACTORIALS[n + 1]
else
Inf
end
end

function fac_big(n::Integer)::BigFloat
if n < 0
throw(DomainError(n, "fac not implemented for n < 0"))
elseif issimplefloat(T)
if n + 1 <= length(FACTORIALS)
convert(T, FACTORIALS[n + 1])
else
T(Inf)
end
else
BigFloat(factorial(big(n)))
float(factorial(big(n)))
end
end

# returns 1/n! for n >= 0
function inv_fac(n::Integer, ::Type{T})::T where T
if issimplefloat(T)
convert(T, inv_fac_f64(n))
else
inv_fac_big(n)
end
end

function inv_fac_f64(n::Integer)::Float64
if n < 0
throw(DomainError(n, "inv_fac not implemented for n < 0"))
elseif n + 1 <= length(INVERSE_FACTORIALS)
INVERSE_FACTORIALS[n + 1]
else
0.0
end
end

function inv_fac_big(n::Integer)::BigFloat
if n < 0
throw(DomainError(n, "inv_fac not implemented for n < 0"))
elseif issimplefloat(T)
if n + 1 <= length(INVERSE_FACTORIALS)
convert(T, INVERSE_FACTORIALS[n + 1])
else
zero(T)
end
else
BigFloat(inv(factorial(big(n))))
float(inv(factorial(big(n))))
end
end
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