PrimeArray: Using arbitrary precision integers to define arrays

primearray.jl

type PrimeArray
	n::BigInt
end

PrimeArray() = PrimeArray(BigInt(1))

function Base.getindex(a::PrimeArray, i::Integer)
	if i < 0 || i > length(Base.PRIMES)
		throw(BoundsError())
	end
	tmp = copy(a.n)
	res = 0
	p = Base.PRIMES[i]
	while mod(tmp, p) == BigInt(0)
		tmp = fld(tmp, p)
		res = res + 1
	end
	return res
end

function Base.setindex!(a::PrimeArray, v::Integer, i::Integer)
	if i < 0 || i > length(Base.PRIMES)
		throw(BoundsError())
	end
	p = Base.PRIMES[i]
	while mod(a.n, p) == BigInt(0)
		a.n = fld(a.n, p)
	end
	a.n = a.n * BigInt(p)^v
	return v
end

a = PrimeArray()
a[1] = 5
a[2] = 7
a[11] = 15

a[1]
a[2]
a[11]