Passing Matrices as params in Launch Files

I'd like to pass the data contained within a matrix as a parameter to several nodes in a launch file. [This link](http://wiki.ros.org/roscpp/Overview/Parameter%20Server#Retrieving_Lists) states how to pass in `std::vector<...>` params for bools, ints, doubles, etc. Is it possible to pass in something like a `std::vector< std::vector>` via the launch file? I'm looking for something similar to [this answer](https://answers.ros.org/question/206146/arrays-ros-launch-file/): given a launch file [[1, 2, 3], [4, 5, 6], [7, 8, 9]] I'd like to recover the value of `matrix` within the node by calling something similar to: std::vector> matrix; nh.getParam("matrix", matrix); This method didn't work when I tried it though. Is there another way this can be done? (I'm using ROS Kinetic on Ubuntu 16.04)