Median Absolute Deviation (MAD)

references

1. https://math.stackexchange.com/questions/113270/the-median-minimizes-the-sum-of-absolute-deviations-the-ell-1-norm

Code

int64_t median_absolute_deviation(std::span<int32_t>&& a) {
    size_t n = a.size();
    int64_t median = a[n / 2];
    return accumulate(begin(a), end(a), int64_t(0),
        [&](const int64_t& x, const int64_t& y) { return x + abs(y - median); });
}