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annotate m-toolbox/classes/+utils/@math/Chi2inv.m @ 19:69e3d49b4b0c database-connection-manager

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Update ltpda_uo.fromRepository
author Daniele Nicolodi <nicolodi@science.unitn.it>
date Mon, 05 Dec 2011 16:20:06 +0100
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1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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2 %
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3 % Compute inverse of the Chi square cumulative distribution function
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4 %
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Daniele Nicolodi <nicolodi@science.unitn.it>
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5 % CALL
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6 %
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7 % x = Chi2inv(p,v);
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8 %
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9 %
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10 % INPUT
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11 %
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12 % - p, probability or significance level
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13 % - v, degrees of freedom of the distribution
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14 %
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15 % Example: If you want the 95% confidence interval for a chi2 variable you
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16 % should call
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17 %
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18 % x = utils.math.Chi2inv([0.05/2 1-0.05/2],v)
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19 %
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20 % References:
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21 % [1] M. Abramowitz and I. A. Stegun, "Handbook of Mathematical
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22 % Functions", Government Printing Office, 1964, 26.4.
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23 %
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24 %
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Daniele Nicolodi <nicolodi@science.unitn.it>
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25 % L Ferraioli 14-02-2011
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26 %
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27 % $Id: Chi2inv.m,v 1.2 2011/05/30 17:18:09 luigi Exp $
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28 %
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29 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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30 function x = Chi2inv(p,v)
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31
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32 a = v/2;
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33 b = 2;
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34 % Call the gamma inverse function.
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35 % x = gaminv(p,v/2,2); % uses statistic toolbox
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36 q = gammaincinv(p,a,'lower');
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37 x = q.*b;
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38
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40 end