How to compute sensitivity kernel

[jollyjokers]

Hi, it's my pleasure to learn about your courses. And I want to compute the sensitivity kernels to get the Jacobian matrix in full waveform inversion using 2D acoustic FD modeling. But when I run the code 7_fdac2d_sensitivity_kernels, it shows the error "name 'K_hom' is not defined". It seems to be that there is no clear calculation in your code. If you could give details of the calculations, it would be greatly appreciated!
Best regards!