粒子图像分割及匹配均为自行编制的子例程，表示出两帧图像间各个像素点的相对情况，该函数用来计算任意函数的一阶偏导数(数值方法)。- Particle image segmentation and matching subroutines themselves are prepared, Between two images showing the relative circumstances of each pixel, This function is used to calculate the