This package implements posit arithmetic, a tapered precision machine number format. Eight new data types are defined, namely Posit8, Posit16, Posit32 and Posit64 for the (linear) posits, a floating-point format, and LogPosit8, LogPosit16, LogPosit32 and LogPosit64 for the logarithmic posits, a logarithmic number system. Internally the C99 library libposit is used for the actual computations for the most part.

Using this package one is able to evaluate posits for real-world applications in terms of precision. Given it is a software implementation the performance is overall worse than the respective usual IEEE 754 floating-point hardware implementations, but it is sufficient to evaluate the formats for reasonably sized numerical benchmarks.

In contrast to SoftPosit.jl this package also offers logarithmic posits and 64-bit precision.

The eight posit number types Posit8, Posit16, Posit32, Posit64 LogPosit8, LogPosit16, LogPosit32, LogPosit64 have been implemented to behave as much as any built-in floating-point type. They are subtypes of AbstractFloat even though logarithmic posits itself are strictly speaking not a floating-point number format, but a logarithmic number system. However, as the majority of numerical code is written to accept AbstractFloats rather than Reals and logarithmic posits share many properties of a typical floating-point number system, this decision was made deliberately and for good reasons.

julia> using Posits

julia> x = Posit8(3.0)
Posit8(3.0)

julia> sqrt(x)
Posit8(1.75)

A wide range of functions are implemented for the number types. If you find a floating-point function you need that is not yet implemented, please raise an issue.

Posits.jl is developed by Laslo Hunhold and licensed under the ISC license. See LICENSE for copyright and license details.