下面这段话不很理解,尤其不明白跟精度有什么关系?这是个很数学的问题，请懂帮我分析一下.非常感谢。

The FDTD algorithm is second-order-accurate by nature of the central-difference approximations used to realize the first-order spatial and temporal derivatives. This leads to a discrete approximation for the fields based on a uniform orthogonal lattice.