namespace StormEigen { /** \eigenManualPage TopicPassingByValue Passing Eigen objects by value to functions Passing objects by value is almost always a very bad idea in C++, as this means useless copies, and one should pass them by reference instead. With Eigen, this is even more important: passing \ref TopicFixedSizeVectorizable "fixed-size vectorizable Eigen objects" by value is not only inefficient, it can be illegal or make your program crash! And the reason is that these Eigen objects have alignment modifiers that aren't respected when they are passed by value. So for example, a function like this, where v is passed by value: \code void my_function(StormEigen::Vector2d v); \endcode needs to be rewritten as follows, passing v by reference: \code void my_function(const StormEigen::Vector2d& v); \endcode Likewise if you have a class having a Eigen object as member: \code struct Foo { StormEigen::Vector2d v; }; void my_function(Foo v); \endcode This function also needs to be rewritten like this: \code void my_function(const Foo& v); \endcode Note that on the other hand, there is no problem with functions that return objects by value. */ }