vector operations

extensions/VectorOperations.h

@@ -93,6 +93,14 @@ namespace vector_operations {
   size_t num_rows(const std::vector<T> &v) {
     return static_cast<size_t>(v.size());
   };
+  template<typename T>
+  size_t num_rows(T &v) {
+    return 1;
+  };
+  template<typename T>
+  size_t num_rows(const T &v) {
+    return 1;
+  };
 
   // num_rows/num_cols for matrix types
   template<typename T>