. Author manuscript; available in PMC: 2020 Apr 2.
Published in final edited form as: Neural Comput. 2016 Mar 4;28(5):882–913. doi: 10.1162/NECO_a_00827
Published under a Creative Commons Attribution 3.0 Unported (CC BY 3.0) license https://creativecommons.org/licenses/by/3.0/deed.