(updated on June 10, 2020)
I was wondering if we could derive numerical relationships between input variables and output variables from nonlinear model structures such neural networks and decision trees. I find a Q&A on ResearchGate, and I like the answer.
One answer wrote: "It is possible to obtain an equation after developing an ANN for prediction. in fact, you will end up with a long equation including the inputs, weights, biases, etc."