Get derivatives of neural network?

Dear all, I construct the non-linear function with multi-layer neural network. The function value itself, is one of my target but also derivatives of function is necessary for me.(it is different to the derivative respect to the weights) However, as far as I found, there is no offered function in neural network toolbox to evaluate the derivative of function.

I have f(x), and I need df/dx. If you have any information for this problem please let me know

Answer 1

[Greg Heath]

A good nnet will yield acceptible estimates of the function for which it is trained. Therefore use

 target = [ f ; g ]

where g is df/dx.

Thank you for formally accepting my answer

Greg