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Greg Heath


3.098 total contributions since 2011

Backgound in Electromagnetic Theory, Plasma Physics and Radar Target Identification using Neural Networks.
PhD Student, Research Assistant and Lecturer at Stanford;
AB, ScB, ScM Student; Research Assistant, Fellow and Professor at Brown;
27 yrs researching Ballistic and Theatre Missile Defense using Neural Networks at MIT Lincoln Laboratory. Retired 2003.

PLEASE DO NOT SEND QUESTIONS AND DATA TO MY EMAIL. HOWEVER, CAN SEND LINKS TO POSTS.
Professional Interests: Neural Netwoks, Spectral Analysis

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Answered
How to check the robustness of the Neural network model?
If you are going to test with white noise, include white noise in your design (i.e., training + validation) Then, given a fixed...

3 Tage ago | 0

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Answered
NARX with Complex Values Input
Decades ago I learned (the hard way) to forget about trying to use complex computations for NNs. However, if you insist, let us...

14 Tage ago | 0

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Why sets Matlab automatically the activation functions for a neural network like this?
That is a standard configuation for a neural net. It's operation is explained in every elementary text. Thank you for formally...

18 Tage ago | 0

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I get a "Performance function replaced with squared error performance" warning when trying to set 'crossentropy' as the performance function.
If you insist on using CROSSENTROPY, try PATTERNNET. Hope this helps. Thank you for formally accepting my answer Greg

29 Tage ago | 0

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How to plot Network performance?
You have lost training information, So the only thing left is output vs input. Hope this helps. Thank you for formally ac...

etwa ein Monat ago | 0

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Elman Neural Network (ENN)
size(P_TRAIN) = [ 1296 1728] size(T_TRAIN) = [ 432 1728] Hope this helps. *Thank you for formally accepting my answer* ...

etwa ein Monat ago | 0

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NARX re-training in closed loop
Using 100 feedback delays makes no sense. Only use feedback delays that are within the correlation length of the function. See...

etwa 2 Monate ago | 1

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Can CNN train separately instead of learning everything at one time?
I try to have the order of inputs as random and uncorrelated as possible. Otherwise the probability of extensive learning/unlear...

etwa 2 Monate ago | 0

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In evaluating a neural net, should NMSE be based only on test subset of data?
For serious work I calulate FOUR values of NMSE: 1.70% Training 2.15% Validation 3.15% Test 4.100% All for 10 (typically...

etwa 2 Monate ago | 0

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Answered
Is the "patternnet" a fully connected neural network
Yes. The only difference between my classifiers and regressors is the sigmoid output layer instead of linear. Hope this helps....

3 Monate ago | 0

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How to train and test time series data in Neural Network Toolbox
I order to test a net you have to compare the actual output with the desired output. Hope this helps. THANK YOU FOR FORMALLY...

3 Monate ago | 0

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Artificial Neural Network implementation and to know the importance of each of the input on output(Response) - wanted help
The way I determine the importance of a single input is 1. Calculate the error using all inputs 2. Loop over inputs ...

3 Monate ago | 0

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Answered
transfer function purelin equation based on neural network toolbox
Read the documentation help purelin doc purelin Greg

3 Monate ago | 0

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How to use a sequenceInputLayer with a regressionLayer (neural networks) ?
The answer is obvious: help regressionlayer doc regressionlayer *Thank you for formally accep...

3 Monate ago | 0

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Time Domain Signal for neural network
If you have rpm I don't see why time is important. However, there is no reason you cannot do both and see what difference it ma...

3 Monate ago | 0

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Answered
Adding hidden layers to a patternnet hurts accuracy?
The global minimum is achievable with a single hidden layer. With more hidden layers you add more local minima; most of which ...

3 Monate ago | 0

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Training neural network - Forward Pass
You are very mixed up. I suggest going to the library and finding a good elementary NN book. Obviously, the appropriate info is...

4 Monate ago | 0

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Hello, I'm working with artificial neural network.
Three layers are sufficient: input/hidden/output The input layer is NOT a neuron layer. The number of input nodes is the dimens...

4 Monate ago | 0

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Why neural network gives negative output ?
How different is the new data (e.g., Mahalanobis distance)? If you know the true outputs, how do the error rates compare? If y...

4 Monate ago | 0

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Answered
Rsq from NMSE in NN
NMSE = mse(trnopdb-net(trnipdb))/MSE00 i.e., NO TRANSPOSES 2. Rsq = R^2 3. Yes. Use separate calculations fo...

4 Monate ago | 1

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Answered
HOW DO I SEARCH IN ANSWERS ???
Oh! It only opens up at the top of the page if the page is sufficiently wide. Since I often use large type and 2 pages per scre...

4 Monate ago | 0

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Answered
Interpolation using Neural Networks
Plot the data. Look at the plots Are there regions that are seasonal? Separate the data that is relevant to your problem Ca...

4 Monate ago | 0

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Answered
How to plot only few classes for confusion matrix?
Oviously, you have to subsample the original matrices. Greg

4 Monate ago | 0

Answered
Open loop Training performance and closed loop training performance are good but multi-step prediction is bad. Reason?
You are not considering information from the autocorrelation fuction. Hope this helps Greg

4 Monate ago | 0

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Formula for two layer FFNN
y1 = b1 + IW1 * x y2 = b2 + LW2 * tanh( y1 ) y3 = b3 + LW3 * tanh( y2 ) = b3 + LW3 * tanh( b2 + LW2 * tanh( b1 + IW1 * x ...

4 Monate ago | 0

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Answered
Input and target have different number of sampel
Train and TTrain have to be transposed. Hope this helps. THANK YOU FOR FORMALLY ACCEPTING MY ANSWER Greg

4 Monate ago | 0

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Answered
How to calculate accuracy for neural network algorithms?
I normalize the mean-square-error MSE = mse(error) = mse(output-target) by the minimum MSE obtained when th...

4 Monate ago | 0

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Neural Network input and targets have different of samples
Transpose both matrices. Thank you for formally accepting my answer Greg

4 Monate ago | 0

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Answered
How these plots (Performance, Training state, Regression) shows the training performance? How to figure out the training rate from these plots?
Training data plots are useful. However, there is no indication of how good the net will perform on nontraining data (THE TRUE ...

4 Monate ago | 0

Answered
Validation check = 0 for traingdm
What you are worrying about is irrelevant. Your data is so good you don't even need a validation subset.The main purpose of a va...

4 Monate ago | 1

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