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1 ## Copyright (C) 1995, 1996, 1997 Kurt Hornik |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 3 of the License, or (at |
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8 ## your option) any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {} chi2inv (@var{x}, @var{n}) |
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21 ## For each element of @var{x}, compute the quantile (the inverse of the |
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22 ## CDF) at @var{x} of the chisquare distribution with @var{n} degrees of |
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23 ## freedom. |
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24 ## @end deftypefn |
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25 |
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26 ## Author: TT <Teresa.Twaroch@ci.tuwien.ac.at> |
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27 ## Description: Quantile function of the chi-square distribution |
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28 |
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29 function inv = chi2inv (x, n) |
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30 |
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31 if (nargin != 2) |
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32 print_usage (); |
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33 endif |
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34 |
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35 if (!isscalar (n)) |
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36 [retval, x, n] = common_size (x, n); |
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37 if (retval > 0) |
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38 error ("chi2inv: x and n must be of common size or scalar"); |
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39 endif |
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40 endif |
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41 |
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42 inv = gaminv (x, n / 2, 2); |
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43 |
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44 endfunction |
