How to get Gradient from Network Created by Neural Network Toolbox?

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Ahmed
Ahmed 2013-6-3
评论： Zheng Chai 2017-12-20
How can the gradient of the performance function with respect to the weights and biases of a neural network created by the Neural Network Toolbox be obtained? I am looking for a function analogous to "getwb".
[x,t] = simplefit_dataset;
net = feedforwardnet(10);
net = train(net,x,t);
wb = getwb(net);
gwb = ????; % something analogous to getwb(net)
% resulting in a 31x1 vector
Thanks, Ahmed

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采纳的回答

Ahmed
Ahmed 2013-6-6
Actully, the function 'staticderivative' can do this for a static network. In general, however, it is likely that defaultderiv is the better choice.
help defaultderiv
help staticderiv

更多回答（1 个）

Greg Heath
Greg Heath 2013-6-3
[x,t] = simplefit_dataset;
net = fitnet; % No need for feedforwardnet
rng(0) % Convenient for duplicating the run
[ net tr ] = train(net,x,t);
wb = getwb(net);
tr = tr % No semicolon...Look at all of the goodies!
stopcrit = tr.stop
bestepoch = tr.best_epoch
gradient = tr.gradient; %complete history
Hope this helps
Thank you for formally accepting my answer
Greg ;
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Greg Heath
Greg Heath 2017-12-19
编辑：Greg Heath 2017-12-19
Sorry, Each year it seems that MATLAB modifies code, presumably to make it better in some esoteric way.
However an annoying result is that the code has become more and more difficult for the average user to understand.
Greg
PS Try contacting MATLAB directly.
Zheng Chai
Zheng Chai 2017-12-20
Thank you so much Greg. Indeed Matlab modified its code. I could not find a proper helper function in my R2013b, but after updating it to R2017b, I found it. Thank you again for your kind help.

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