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1 <html>
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2 <head>
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3 <title>
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4 Netlab Reference Manual nethess
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5 </title>
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6 </head>
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7 <body>
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8 <H1> nethess
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9 </H1>
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10 <h2>
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11 Purpose
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12 </h2>
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13 Evaluate network Hessian
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14
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15 <p><h2>
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16 Synopsis
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17 </h2>
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18 <PRE>
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19 h = neterr(w, net, x, t)
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20 [h, varargout] = neterr(w, net, x, t, varargin)
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21 </PRE>
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22
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23
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24 <p><h2>
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25 Description
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26 </h2>
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27
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28 <p><CODE>h = nethess(w, net, x, t)</CODE> takes a weight vector <CODE>w</CODE> and a network
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29 data structure <CODE>net</CODE>, together with the matrix <CODE>x</CODE> of input
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30 vectors and the matrix <CODE>t</CODE> of target vectors, and returns the
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31 value of the Hessian evaluated at <CODE>w</CODE>.
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32
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33 <p><CODE>[e, varargout] = nethess(w, net, x, t, varargin)</CODE> also returns any additional
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34 return values from the network Hessian function, and passes additional arguments
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35 to that function.
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36
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37 <p><h2>
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38 Example
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39 </h2>
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40
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41 <p>In <CODE>evidence</CODE>, this function is called once to compute the
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42 data contribution to the Hessian
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43 <PRE>
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44
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45 [h, dh] = nethess(w, net, x, t, dh);
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46 </PRE>
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47
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48 and again to update the Hessian for new values of the hyper-parameters
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49 <PRE>
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50
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51 h = nethess(w, net, x, t, dh);
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52 </PRE>
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53
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54
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55 <p><h2>
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56 See Also
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57 </h2>
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58 <CODE><a href="neterr.htm">neterr</a></CODE>, <CODE><a href="netgrad.htm">netgrad</a></CODE>, <CODE><a href="netopt.htm">netopt</a></CODE><hr>
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59 <b>Pages:</b>
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60 <a href="index.htm">Index</a>
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61 <hr>
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62 <p>Copyright (c) Ian T Nabney (1996-9)
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63
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64
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65 </body>
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66 </html> |
