annotate toolboxes/FullBNT-1.0.7/netlab3.3/mlpinit.m @ 0:e9a9cd732c1e tip

first hg version after svn
author wolffd
date Tue, 10 Feb 2015 15:05:51 +0000
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wolffd@0 1 function net = mlpinit(net, prior)
wolffd@0 2 %MLPINIT Initialise the weights in a 2-layer feedforward network.
wolffd@0 3 %
wolffd@0 4 % Description
wolffd@0 5 %
wolffd@0 6 % NET = MLPINIT(NET, PRIOR) takes a 2-layer feedforward network NET and
wolffd@0 7 % sets the weights and biases by sampling from a Gaussian distribution.
wolffd@0 8 % If PRIOR is a scalar, then all of the parameters (weights and biases)
wolffd@0 9 % are sampled from a single isotropic Gaussian with inverse variance
wolffd@0 10 % equal to PRIOR. If PRIOR is a data structure of the kind generated by
wolffd@0 11 % MLPPRIOR, then the parameters are sampled from multiple Gaussians
wolffd@0 12 % according to their groupings (defined by the INDEX field) with
wolffd@0 13 % corresponding variances (defined by the ALPHA field).
wolffd@0 14 %
wolffd@0 15 % See also
wolffd@0 16 % MLP, MLPPRIOR, MLPPAK, MLPUNPAK
wolffd@0 17 %
wolffd@0 18
wolffd@0 19 % Copyright (c) Ian T Nabney (1996-2001)
wolffd@0 20
wolffd@0 21 if isstruct(prior)
wolffd@0 22 sig = 1./sqrt(prior.index*prior.alpha);
wolffd@0 23 w = sig'.*randn(1, net.nwts);
wolffd@0 24 elseif size(prior) == [1 1]
wolffd@0 25 w = randn(1, net.nwts).*sqrt(1/prior);
wolffd@0 26 else
wolffd@0 27 error('prior must be a scalar or a structure');
wolffd@0 28 end
wolffd@0 29
wolffd@0 30 net = mlpunpak(net, w);
wolffd@0 31