Add ESS information in regression ex

benchmark/regression_autoppl.cpp

@@ -5,6 +5,7 @@
 #include <autoppl/expression/expr_builder.hpp>
 #include <autoppl/mcmc/hmc/nuts/nuts.hpp>
 #include <benchmark/benchmark.h>
+#include <autoppl/math/ess.hpp>
 
 namespace ppl {
 
@@ -49,6 +50,13 @@ static void BM_Regression(benchmark::State& state) {
 		ppl::nuts(model, config);
     }
 
+    arma::cube out(storage.n_rows,
+                   storage.n_cols,
+                   1);
+    out.slice(0) = storage;
+    arma::vec ess_res = math::ess(out);
+    ess_res.print("ESS");
+
     // print mean and stddev results
 	std::cout << "Bias: " << arma::mean(storage.col(3)) << std::endl;
 	std::cout << "Alcohol: " << arma::mean(storage.col(0)) << std::endl;