Retrieving the saddle-splay elastic constant K24 of nematic liquid crystals from an algebraic approach Sébastien Fumeron, Fernando Moraes and Erms Pereira Eur. Phys. J. E, 39 9 (2016) 83 Published online: 06 September 2016 DOI: 10.1140/epje/i2016-16083-8