If I want to calculate a number proportional to how badly a new measurement fits a prediction, if I just had an uncertainty double (i.e. assume circular gaussian distribution) I could divide distance by that uncertainty and be done
hmm, as far as static constexpr vs constexpr at global/namespace scope, it seems like the emitted binary is identical, but if inside struct/class scope it must be static constexpr plain constexpr won't compile
static constexpr int N = 42 vs constexpr int N = 42, in a header, at global or namespace scope. Any difference at all? e.g. constexpr can have issues where the optimizer may remove the memory location of the data causing linking errors if the owning cc file does not use/define it