I calculated the Jacobian matrix. I guess one of the line should be full of -0.97 since one of the function is 29.927071171061 - 0.97*t and the derivative of it is just -0.97. But only one element of the Jacobian matrix has a value of -0.97. Could you explain why?

Welcome

Are you aware that you put a 5x5 rank-1 matrix as the first argument into your function `FOCs`

?

`[t t t t t]`

where `t = ss_vec`

does give you just that. If that’s what you actually meant, I think the answer depends on the actual definition of `FOCs`

(note that a minimal working example that can be *copy-pasted* would make it a lot easier for people to help you. Please look also here for some other recommendations: Please read: make it easier to help you)