fix if input vector size is 1

Author: tell

include/clt/benchmark2.hpp

@@ -80,6 +80,10 @@ template <class T> inline auto calc_stats(const T &data)
          }),
          fp_data.begin());
     const auto [smean, uvar] = mean_and_sample_variance(fp_data);
+    if (data.size() < 2) {
+        const auto point = fp_data[0] ? fp_data.size() == 0 : 0.0;
+        return std::make_tuple(smean, uvar, point, 0.0, 0.0);
+    }
     const auto smedian = median(fp_data);
     const auto smad = median_absolute_deviation(fp_data, smedian);
     const auto siqr = interquartile_range(fp_data);