MATLAB neural network implementation

[etileyli]

Hi all!!

I have a problem on implementing a neural network in MATLAB with using addition and multiplication.

I'm trying to implement the network below,

p = [1 3];
t = [2 4];
net = newff(p,t,1);
net = train(net, p,t);
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after running the code above, I fetch the weights and biases with

input_weights = net.IW;
layer_weights = net.LW;
biases = net.b;

write a function " try_neural" with resulting weights

function [net_out] = try_neural(in_1)
w_1_1 = -1.47057806618821; b_1 = 0.0252873414230115;
L1_out = tansig(in_1*w_1_1 + b_1);
wo_1 = -1.11163638238458; b_o = 0.00535792495355342;
net_out = L1_out*wo_1 + b_o;

then run the line : result = try_neural (1);

I'm getting different results with
result = sim(net,1);

Most probably I'm missing something very basic and simple but I can't figure out the source of error. (I'm using MATLAB 2010b)

Thanks in advance!!