Sharif University of Technology

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Assignment 3
Use
MATLAB NEURAL NETWORKS TOOLBOX
or the
Neunet (Desire)
system to develop and study Learning process in Back-Propagation networks.
1. Train the 2-2-1 network to learn the XOR patterns.
2. Modify the 2-2-1 network so that only one hidden unit is used.
3. Train the 2-2-1 network to learn the XOR patterns when the Bias term is fixed at zero. (Note that you must modify a few statements in the program to accomplish this)
4. Do not randomize the weights before training the 2-2-1 network. (Remove the initialization to random values statements by default, the weights will be initialized to zero)
5. Modify the program to include a Temperature parameter. Then, train the 2-2-1 network with several different Temperature parameter values.
Questions
1. How many epochs are required to learn the patterns correctly
2. Does the system converge to the same set of weights after each learning session
3. What is the effect of the learning rate (Lrate) on the speed of learning
4. What is the effect of setting the initial weights to zero
5. Can the Network learn the patterns without a Bias term
6. What is the effect of the Temperature parameter on the speed of learning
7. Did you encounter any local minima for which there were global minima of zero

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