====== StateVector ======

StateVectors are vector objects similar to GSL vector types which store floating point numbers. In Auryn they are used in a [[NeuronGroup]] to store the state of all neurons and Auryn implements functions to monitor them or to save and load them to/from disc. Typically each neuron model will at least have one such vector storing the membrane potential. [[SpikingGroup]] implements a set of generic mechanism to create or retrieve such vectors. The probably most useful one is 
<code cpp>
auryn_vector_float * get_state_vector(string key);
</code>
which will return a StateVector corresponding to its ''key'' or specifier. For instance ''mem'' is the [[default specifier]] for the membrane potential. Note, that ''get_state_vector'' should typically only be called during initialization of a group and not in the [[evolve]] method of any [[NeuronGroup]], because the call is relatively costly.