Could you explain how to calculate the second derivative 'dxy' ?

[seekFire]

In inference.py, function taylor, the 2nd derivative dxy is calculated by:

dxy = 0.25 * (hm[py+1][px+1] - hm[py-1][px+1] - hm[py+1][px-1] + hm[py-1][px-1])

So could you explain why is the equation like this?

[bigbrother33]

same question - -

[hbin-ac]

dx[px, py] = (hm[px+1, py] - hm[px -1, py]) / 2 dxy[px, py] = (dx[px, py+1] - dx[px, py-1]) / 2 = (hm[py+1, px+1] - hm[py-1, px+1] - hm[py+1, px-1] + hm[py-1, px-1]) / 4

[seekFire]

@hbin-ac I got it! Thank you very much!