I have an expression involving subscripted variables, x_i (and constants, b_k,c_k,d_k). I would like to compute the Jacobian but the most straightforward application of the D operator, D[f,x[k]] always returns 0.
I want to compute \partial^2 f/\partial{x_i}\partial{x_j}.
Any help greatly appreciated.
Thanks – Len B
Len:
Check out the docs for Subscript[].
I believe your issue is that b[t] (and similar expressions) is being interpreted as a function call, not a subscripted variable.
Have a great 2021.
Sounds like a neat idea, I must have forgotten about the notation package, maybe because it was imho not well documented. Not well enough so that I could understand.