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Greg Heath


3,073 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 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...

6 days ago | 0

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

6 days ago | 0

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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 ...

7 days ago | 0

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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...

10 days ago | 1

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Expressing equation in terms of sin/cos
If you substitute your solutions into LHS and get the RHS, then it is possible. Greg

11 days ago | 0

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How to decide window size for a moving average filter?
I'm very surprised that none of the previous responses mentioned 1. Determine characteristic self correlation lengths usi...

12 days ago | 0

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finding optimal neural network architecture using genetic algorithms
0. The genetic approach is a waste of time. It takes too long. 1.Typically, a single hidden layer is sufficient. 2. Minimize t...

23 days ago | 0

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Neuron Network input variables-Missing data
Sorry: You have to predict the missing data as best you can. Greg

23 days ago | 0

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Why my network is not giving the desired output
Design(training+validation), test and new data should all have the same summary statistics BEFORE NORMALIZATION. This may requir...

30 days ago | 0

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How to predict future responses y(t + 1) from the training of a narxnet network with past data of x (t) and y (t)? (NARXNET)
YOU DO NOT HAVE X and Y !!! YOU HAVE X and T where T = Ydesired Hope this helps Thank you for formally accepting m...

1 month ago | 1

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Testing a Backpropagation Neural Network
You are probably OVERTRAINING AN OVERFIT NET OVERFITTING: Using more unknown hidden nodes than number ...

1 month ago | 0

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The performance of hidden neurons
I think I misinterpreted the question. Now I think you mean when I increase the number of hidden nodes from 4 to 5 why do I star...

1 month ago | 0

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Crossentropy loss function - What is a good performance goal?
These equations are not necessarily precise. For example: data = design + test design = training + validation In partic...

1 month ago | 0

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How can two neural networks be compared for regression based on training and testing results ?
The MATLAB default is training/validation/testing fractions of 0.7/0.15/0.15 Typically, the performance depends on a 1. A...

1 month ago | 0

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what types of Network and training are suitable for returning a more precise value?
Plot your targets vs your inputs to see if some of the inputs are not worth using. and/or you can try rejecting inputs based ...

1 month ago | 0

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Issue while mapping weights to a New Feedforward Neural network created using newff
You need to add another component equal to unity to account for a bias weight. Thank you for formally accepting m answer. ...

1 month ago | 0

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how to adjust derivatives of backpropagation according to custom error function
Your error function is not at a minimum when output = target Why did you not use the standard E = (output - target)^2 ...

1 month ago | 0

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How to compute gradients using the Neural Network Toolbox software?
help gradient doc gradient Thank you for formally accepting my answer Greg

2 months ago | 0

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An error occurred while trying to determine whether "readData" is a function name.
>> help readData readData not found >> doc readData SUCCESS !!! Hope this helps THANK YOU FOR FORMALLY ACCEPTING MY A...

2 months ago | 0

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Create neural Network with multiple outputs
See my comment. Greg

2 months ago | 0

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Overfitting of Regression Plot for a Feedforward Neural Network
OVERFITTING IS NOT "THE" PROBLEM !!! In general, the problem is OVERTRAINING an overfit net. My solution is simple: DO NOT OV...

2 months ago | 0

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Answered
Neural Network Last Layer Shows a Different Number of Outputs
Line 2: target, not output trainFcn is undefined. I get 15, not 13 in the figure Hope this helps. Thank you for formal...

2 months ago | 0

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When I should stop training a neural network?
The danger is OVERTRAINING an OVERFIT NET. There are several approaches. 1. PREVENT OVERFITTING the I-H-O net by ...

2 months ago | 0

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Artificial Neural Network questions
The typical NN has a set of input nodes ( which for some reason is not defined to be a layer !!! ), a middle layer and an outpu...

2 months ago | 0

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Answered
Do Multiple Output Neural Networks share the same weights and biases?
The similarity or orthogonality of the outputs tends to be irrelevant. If two set of outputs are not caused by a significant ...

2 months ago | 0

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Answered
What is the difference between pca and processpca commands?
help pca doc pca help processpca doc processpca Hope this helps Thank you for formally accepting my answer Greg

2 months ago | 0

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Difference between 2D input and multiple input with recurrent neural networks for time series
Written MATLAB should treat the cases the same. Unfortunately I don't have time to prove it Greg

2 months ago | 1

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how can i train my network for test and validation data?
The MATLAB default AUTOMATICALLY splits the data into TRAINING + VALIDATION+TEST SUBSETS in the ratios 0.7/0.15/0.15. For r...

2 months ago | 0

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Best Neural Network for Multivariate Regression
Use FITNET. Accept all parameter settings. Train 10 models with different random initial weights If unsuccessful. Repeat wi...

2 months ago | 0

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Answered
how can i train my network for test and validation data?
Where is your training data? The MATLAB default is a random choice of trn/val/tst = 0.7/0.15/0.15 I choose candidate values ...

2 months ago | 0

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