Equation extraction in an Artificial Neural Network

I am a newbie in ANN's. I have a relatively large model which comprises of 15 independent variables (inputs) and one dependent variable (output). Since i do not know the exact relationship between the inputs and the output I am trying to use an ANN for curve fitting . I have a vast amount of training data so as to train the network. I would like to know how to extract the regression equation between the inputs and output because i want to know the exact mathematical relationship that describes my model. I have studied the answers, that have been in this forum, regarding the extraction of the regression equation but i want to know how to find the regression equation between the raw data (namely non normalized inputs, output) ?

Thank you

Answer 1

[Greg Heath]

There is no way to use data to determine the analytic form of particular function without prior information.

For typical data, the analytic form for a universal approximator neural network is

 y = B2 + LW*tanh(B2+IW*x)

Hope this helps.

Greg