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1 function g=gcvplot(alpha,varargin)
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2 %
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3 % Computes and plots the Generalized Cross-Validation score (GCV)
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4 % for local fits with different smoothing parameters.
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5 %
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6 % The first argument to gcvplot(), alpha, should be a matrix with one
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7 % or two columns (first column = nearest neighbor component, second
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8 % column = constant component). Each row of this matrix is, in turn,
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9 % passed as the 'alpha' argument to gcv() (and locfit()). The results
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10 % are stored in a matrix, and GCV score ploted against the degrees of
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11 % freedom.
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12
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13 k = size(alpha,1);
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14 z = zeros(k,4);
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15
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16 for i=1:k
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17 z(i,:) = gcv(varargin{:},'alpha',alpha(i,:));
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18 end;
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19
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20 plot(z(:,3),z(:,4));
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21 xlabel('Fitted DF');
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22 ylabel('GCV');
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23
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24 g = [alpha z];
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25 return;
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