Julia Ramanujan Approximation for Pi

julia_ramanujan_pi.jl

using Core: BigInt
using Base: Int64, Float64


function fact(n::BigInt)
    if n <=1 return 1 end
    return n * fact(n-1)
end

println(fact(12))

function ramanujan_approximation(max_k::BigInt)
    
    constant = 2*sqrt(2) / 9801
    val::Float64 = 0
    
    for k in 0:max_k
        iteration::Float64 = (fact(4*k) * (1103 + 26390*k)) / (fact(k)^4 * 396^(4*k) ) 
        val += iteration
    end
    
    return (constant * val)
end

onebypi = ramanujan_approximation(2)

println(onebypi, " ", 1/onebypi)