A SIMPLIFIED TWO-NODE COARSE-MESH FINITE DIFFERENCE METHOD FOR PIN-WISE CALCULATION WITH SP3Wenbo Zhao, Yingrui Yu, Xiaoming Chai, Zhonghao Ning, Bin Zhang, Yun Cai, Kun Liu, Xingjie Peng and Junchong YuEPJ Web Conf., 247 (2021) 02023DOI: https://doi.org/10.1051/epjconf/202124702023