diff --git a/src/main.cpp b/src/main.cpp
index 3392a599b9acd3976579f2da513f57c316f99e90..db5fd9824a15545333a0c96ac173e03754d5c719 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -293,6 +293,18 @@ int main(int argc, char *argv[])
      }
      }
 
+     { // gnuplot output for entropy (gaz parfait en prenant cv = 1))
+     const Kokkos::View<const Rd*> xj   = mesh_data.xj();
+     const Kokkos::View<const double*> rhoj = unknowns.rhoj();
+     const Kokkos::View<const double*> pj = unknowns.pj();
+     const Kokkos::View<const double*> gammaj = unknowns.gammaj();
+     std::ofstream fout("S");
+     fout.precision(15);
+     for (size_t j=0; j<mesh.numberOfCells(); ++j) {
+       fout << xj[j][0] << ' ' << std::log(pj[j]*std::pow(rhoj[j],-gammaj[j])) << '\n';
+     }
+     }
+
   }
 
   Kokkos::finalize();