#!/usr/bin/env julia

# Jacek Poziemski 272389

"""
    exponentsequal(x::Float64, y::Float64)

Check if the exponents of 2 64-bit IEEE 754
numbers are equal.

# Arguments
- `x::Float64`: first of the 2 numbers to check
- `y::Float64`: second of the 2 numbers to check
"""
function exponentsequal(x::Float64, y::Float64)
    xexp = SubString(bitstring(x), 2:12)
    yexp = SubString(bitstring(y), 2:12)

    return xexp == yexp
end

"""
    numberdistribution(start::Float64, finish::Float64)

Calculate the step between 2 neighbouring
64-bit IEEE 754 numbers in a given range.

# Arguments
- `start::Float64`: bottom bound of the range
- `finish::Float64`: upper bound of the range
"""
function numberdistribution(start::Float64, finish::Float64)
    if !exponentsequal(nextfloat(start), prevfloat(finish))
        return missing
    end

    exp = parse(Int, SubString(bitstring(start), 2:12), base = 2)

    return 2.0^(exp - 1023) * 2.0^(-52)
end

println("[1.0, 2.0]: $(numberdistribution(1.0, 2.0))")
println("2^(-52): $(2.0^(-52))")
println("[0.5, 1.0]: $(numberdistribution(0.5, 1.0))")
println("2^(-53): $(2.0^(-53))")
println("[2.0, 4.0]: $(numberdistribution(2.0, 4.0))")
println("2^(-51): $(2.0^(-51))")