How to get the equation for trained Neural Network Toolbox

I have trained my neural network and extracted the weights.

Using the weights, I constructed the equation to get the output value, however, I'm not getting the same value as the value predicted from Matlab. I wonder where I go wrong:

weights = cell(3,1)

biases = net.b

x1 = [1.5527; -1.2526; -1.1460]

w1 = weights{1} % 20x3

b1 = biases{1} % 20x1

intermediate = w1*x1 + b1

y1_0_y1_19 = tansig(intermediate); % Layer 1

x2 = y1_0_y1_19; % 20x1

w2 = weights{2}; % 10x20

b2 = biases{2}; % 10x1

intermediate2 = w2*x2 + b2 % 10 x 1

y2_0_y2_10 = tansig(intermediate2); % Layer 2

x3 = y2_0_y2_10; % 10 x 1

w3 = weights{3}; % 1x10

b3 = biases{3}; % 1x1

intermediate3 = w3*x3 + b3 % 1 x 1

y3 = intermediate3; % Layer 3

However the y3 that I got is different from the output of the network when I run the following net(x1).

Can someone tell where I went wrong in my formulation to the output value y3?

Answer 1

[Steven Lord]

You haven't shown your network so I can't be certain but I'm guessing you forgot the pre- and post-processing steps.

[Lune T]

Thanks Steven!

As your suggestion, I applied the pre and post processing steps: which in my case was applying mapminmax on my inputs and reversing it at the outputs and the problem was fixed.

Really appreciate the help!

[Eugene Pashinov]

could you please show final code that works?