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Compositional Numeric Library


The Compositional Numeric Library (CNL) is a C++ library of fixed-precision numeric classes which enhance integers to deliver safer, simpler, cheaper arithmetic types. Documentation can be found here. You can try out CNL on Compiler Explorer here.

CNL is particularly well-suited to:

  • compute or energy-constrained environments where FPUs are absent or costly;
  • compute or energy-intensive environments where arithmetic is the bottleneck such as simulations, machine learning applications and DSPs; and
  • domains such as finance where precision is essential.


The latest version of CNL requires a C++20-compatible tool chain. (Version 1.x supports C++11.) CNL is tested on the following systems:



  • GCC 10 / Clang 10, 11
  • CMake 3.16
  • Conan 1.32



  • GCC 10 / Clang 11
  • CMake 3.16
  • Conan 1.35



  • Visual Studio 2019 Version 16.8
  • CMake 3.8.0
  • Conan 1.35



The library is hosted on GitHub:

git clone
cd cnl


CMake scripts are provided.

  • To build and install CNL on your system:
mkdir build && cd build
cmake ..
cmake --build . --target install

Note: you may need user privileges to install the library. Alternatively, you can install to user directory using CMAKE_INSTALL_PREFIX:

mkdir build && cd build
cmake -DCMAKE_INSTALL_PREFIX:FILE=/home/username/someplace ..
cmake --build . --target install

Alternatively, CNL is a header-only library so you can simply point to the include directory

c++ -isystem /path/to/cnl/include -std=c++20 my_program.cpp

or even include the root header directly in your code:

#include "/path/to/cnl/include/cnl/all.h"


The test suite uses CMake and depends on Google Test and Google Benchmark. Optional integration tests use Boost.Multiprecision and Boost.SIMD.

  1. Conan can be used to pull in essential dependencies. This example assumes GCC but other tool chain files are provided:

    cd build
    conan profile new --detect --force default
    conan profile update settings.compiler.libcxx=libstdc++11 default  # GCC only
    conan profile update settings.compiler.cppstd=20 default
    conan install --build=missing --options test=unit ..

    ... and then configure, build and run unit tests:

    conan build --configure --build --test ..
  2. To run benchmarks, use --options test=benchmark...

    conan install --build=missing --options test=benchmark ..

    then configure and build

    conan build --configure --build ..

    and finally run explicitly to see the results.



The API is exposed through headers in the include directory. Add this to your system header list and include, e.g.:

// to use a specific type:
#include <cnl/scaled_integer.h>

// or to include all CNL types:
#include <cnl/all.h>

Example Projects

Examples of projects using CNL:

  • CDSP - Compositional DSP Library for C++;
  • BrewBlox firmware - firmware for a brewery controller
  • cnl_example - minimal CMake-based project which uses CNL as a dependency.

Further Reading


  • Much of the simplicity and efficiency in CNL's API design can be traced back to Matheus Izvekov's fp fixed point library.
  • Together with Lawrence Crowl's fixed-point paper, P0106, it lays the groundwork for integer-backed real number approximation that minimizes loss of performance and precision.
  • fpm is a fixed-point math library with a high quantity of mathematical functions.
  • Fixed Point Class is a single-header C++98 solution from Peter Schregle's.

Contact Information

All feedback greatly appreciated.

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