Numerically solving generated Jacobian equations in freeform optical design Lotte B. Romijn, Martijn J.H. Anthonissen, Jan H.M. ten Thije Boonkkamp and Wilbert L. IJzerman EPJ Web Conf., 238 (2020) 02001 Published online: 20 August 2020 DOI: 10.1051/epjconf/202023802001