Re: [boost] additional math-functions

Yes, that's why I asked which C++ standard can be used. Can I use e.g. C++14 unless you can make a really good case why the code needs something else. - concepts I'd prefer not to. - lambdas Yes absolutely. - constexpr if

In constexpr versions of functions yes - the existing ccmath code requires C++17, so you're on safe ground there.  For general runtime special functions I'd prefer it if we can all keep to C++14 for the moment so there's not too much divergence between different functions. John.