Performance: Possibility to use std::reduce or std::accumulate instead of raw loop

[krishnakumarg1984]

In sdmm.h, it looks like a standard accumulation operation is implemented with a raw loop.

    for (auto const &transform : this->transforms())
      out += transform.adjoint() * static_cast<t_Vector>(transform * input);

Might be possible to use std::accumulate or std::reduce (parallelised in C++17). Thoughts?