How to choose "Nlocmin,Nlocmax" in non linear regression and curve fitting?

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How can one choose "Nlocmin and Nlocmax" values for non linear regression using ANN feedforwardnet in the code mentioned by Greg sir??
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2. Estimate, by trial and error, the minimum number of hidden nodes necessary for successfully approximating the underlying input-output transformation. For a smooth function with Nlocmin local minima and Nlocmax local maxima, a reasonable lower
bound is H >= 2*max(Nlocmin,Nlocmax). Sometimes it is prudent to count endpoint extrema as 1/2 a local extremum. The addition of real-world noise, interference and measurement error should not change that minimum number. However, the contamination may make it difficult to identify the significant error-free extrema.

Accepted Answer

Greg Heath
Greg Heath on 28 Mar 2015
Edited: Greg Heath on 28 Mar 2015
Plot the target and count the number of local extrema.
This will only work for relatively smooth functions.
Otherwise use the search over
Hmin:dH:Hmax < Hub
with a preference for Hmax << Hub
For details, search NEWSGROUP and ANSWERS using
greg Hub
Hope this helps
Thank you for formally accepting my answer
Greg Heath
Greg Heath on 4 Apr 2015
1. Initialize the random number state before the loops and choose the 38th after that
2. Store the random number state before each design
3. Store the random number state and corresponding net if the new MSE is smaller than the previous minimum.

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