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 arbitrary function of the first order partial derivative (numerical