also worth mentioning here is Vc - portable, zero-overhead C++ types for explicitly data-parallel programming
https://github.com/VcDevel/Vc/ (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p021...).
Custom licenses are a headache and I always wonder whether the academics who promulgate them wonder why no-one uses their software.