Do not use size_t

src/one-body-sample.cc

@@ -81,7 +81,7 @@ int main() {
     VectorType f(grid.size(grid.maxLevel(), dim));
     // Fill right-hand side with semi-random numbers
     for (size_t i = 0; i < f.size(); ++i)
-      for (size_t j = 0; j < dim; ++j)
+      for (int j = 0; j < dim; ++j)
         f[i][j] = 300;
 
     VectorType u1(grid.size(grid.maxLevel(), dim));