[Erlangen]

You said "ranges and algorithms", but you didn't copy the third function which actually uses <range> library.

inline double ranges_pipeline(std::span<double const> xs) noexcept { auto costs = xs | std::views::transform(calibrated_mv) | std::views::transform(residual) | std::views::transform(weighted_square);

  return std::ranges::fold_left(costs, 0.0, std::plus<double>{});

}

It's still a bit verbose, because C++ doesn't allow universal function call syntax. It will be even more concise in other languages like D.

[Joker_vD]

That version was so much more opaque that I didn't bother copying that. Again, I'm not entirely sure why people are so enamored with splitting iteration itself from the contents of one iteration step, especially since the loops are language built-ins.