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1 function lfband(fit,varargin)
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2
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3 % adds confidence bands around the plot of a locfit() fit.
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4 %
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5 % for 2-d fits, produces separate surface plots of upper and
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6 % lower confidence limits.
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7 %
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8 % Bands are based on 95% pointwise coverage, using a single
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9 % (i.e. global) estimate of sigma^2.
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10
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11 xfit = lfmarg(fit);
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12 % placing 'band','g' before varargin{:} ensures that
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13 % user-provided 'band' has precedence.
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14 ypp = predict(fit,xfit,'band','g',varargin{:});
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15 yfit = ypp{1};
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16 se = ypp{2};
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17 bands = ypp{3};
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18
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19 data = fit.data;
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20 xdata = data.x;
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21 p = size(xdata,2);
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22 cv = 1.96;
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23 fali = fit.fit_points.family_link;
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24 cl = invlink(bands(:,1),fali);
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25 cu = invlink(bands(:,2),fali);
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26
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27 if (p==1)
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28 hold on;
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29 plot(xfit{1},cu,':');
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30 plot(xfit{1},cl,':');
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31 hold off;
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32 end;
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33
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34 if (p==2)
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35 x1 = xfit{1};
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36 x2 = xfit{2};
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37 figure(1);
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38 surf(x1,x2,reshape(cl,length(x1),length(x2))');
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39 figure(2);
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40 surf(x1,x2,reshape(cu,length(x1),length(x2))');
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41 end;
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42
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43 return;
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