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Netlab Reference Manual gtminit
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<H1> gtminit
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<h2>
Purpose
</h2>
Initialise the weights and latent sample in a GTM.

<p><h2>
Synopsis
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<PRE>
net = gtminit(net, options, data, samptype)
net = gtminit(net, options, data, samptype, lsampsize, rbfsampsize)
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<p><h2>
Description
</h2>
<CODE>net = gtminit(net, options, data, samptype)</CODE> takes a GTM <CODE>net</CODE>
and generates a sample of latent data points and sets the centres (and
widths if appropriate) of
<CODE>net.rbfnet</CODE>.

<p>If the <CODE>samptype</CODE> is <CODE>'regular'</CODE>, then regular grids of latent
data points and RBF centres are created.  The dimension of the latent data
space must be
1 or 2.  For one-dimensional latent space, the <CODE>lsampsize</CODE> parameter
gives the number of latent points and the <CODE>rbfsampsize</CODE> parameter
gives the number of RBF centres.  For a two-dimensional latent space,
these parameters must be vectors of length 2 with the number of points
in each of the x and y directions to create a rectangular grid.  The
widths of the RBF basis functions are set by a call to <CODE>rbfsetfw</CODE>
passing <CODE>options(7)</CODE> as the scaling parameter.

<p>If the <CODE>samptype</CODE> is <CODE>'uniform'</CODE> or <CODE>'gaussian'</CODE> then the
latent data is found by sampling from a uniform or
Gaussian distribution correspondingly.  The RBF basis function parameters
are set
by a call to <CODE>rbfsetbf</CODE> with the <CODE>data</CODE> parameter
as dataset and the <CODE>options</CODE> vector.

<p>Finally, the output layer weights of the RBF are initialised by
mapping the mean of the latent variable to the mean of the target variable,
and the L-dimensional latent variale variance to the variance of the
targets along the first L principal components.

<p><h2>
See Also
</h2>
<CODE><a href="gtm.htm">gtm</a></CODE>, <CODE><a href="gtmem.htm">gtmem</a></CODE>, <CODE><a href="pca.htm">pca</a></CODE>, <CODE><a href="rbfsetbf.htm">rbfsetbf</a></CODE>, <CODE><a href="rbfsetfw.htm">rbfsetfw</a></CODE><hr>
<b>Pages:</b>
<a href="index.htm">Index</a>
<hr>
<p>Copyright (c) Ian T Nabney (1996-9)


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author	wolffd
date	Tue, 10 Feb 2015 15:05:51 +0000
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