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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 2, or (at your option) |
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8 ## 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, write to the Free |
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17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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18 ## 02110-1301, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} frnd (@var{m}, @var{n}, @var{r}, @var{c}) |
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22 ## @deftypefnx {Function File} {} frnd (@var{m}, @var{n}, @var{sz}) |
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23 ## Return an @var{r} by @var{c} matrix of random samples from the F |
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24 ## distribution with @var{m} and @var{n} degrees of freedom. Both |
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25 ## @var{m} and @var{n} must be scalar or of size @var{r} by @var{c}. |
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26 ## If @var{sz} is a vector the random samples are in a matrix of |
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27 ## size @var{sz}. |
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28 ## |
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29 ## If @var{r} and @var{c} are omitted, the size of the result matrix is |
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30 ## the common size of @var{m} and @var{n}. |
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31 ## @end deftypefn |
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32 |
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33 ## Author: KH <Kurt.Hornik@wu-wien.ac.at> |
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34 ## Description: Random deviates from the F distribution |
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35 |
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36 function rnd = frnd (m, n, r, c) |
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37 |
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38 if (nargin > 1) |
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39 if (!isscalar(m) || !isscalar(n)) |
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40 [retval, m, n] = common_size (m, n); |
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41 if (retval > 0) |
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42 error ("frnd: m and n must be of common size or scalar"); |
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43 endif |
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44 endif |
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45 endif |
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46 |
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47 |
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48 if (nargin == 4) |
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49 if (! (isscalar (r) && (r > 0) && (r == round (r)))) |
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50 error ("frnd: r must be a positive integer"); |
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51 endif |
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52 if (! (isscalar (c) && (c > 0) && (c == round (c)))) |
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53 error ("frnd: c must be a positive integer"); |
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54 endif |
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55 sz = [r, c]; |
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56 |
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57 if (any (size (m) != 1) && |
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58 ((length (size (m)) != length (sz)) || any (size (m) != sz))) |
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59 error ("frnd: m and n must be scalar or of size [r,c]"); |
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60 endif |
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61 elseif (nargin == 3) |
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62 if (isscalar (r) && (r > 0)) |
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63 sz = [r, r]; |
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64 elseif (isvector(r) && all (r > 0)) |
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65 sz = r(:)'; |
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66 else |
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67 error ("frnd: r must be a postive integer or vector"); |
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68 endif |
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69 |
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70 if (any (size (m) != 1) && |
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71 ((length (size (m)) != length (sz)) || any (size (m) != sz))) |
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72 error ("frnd: m and n must be scalar or of size sz"); |
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73 endif |
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74 elseif (nargin == 2) |
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75 sz = size(a); |
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76 else |
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77 usage ("frnd (m, n, r, c)"); |
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78 endif |
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79 |
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80 |
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81 if (isscalar (m) && isscalar (n)) |
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82 if ((m > 0) && (m < Inf) && (n > 0) && (n < Inf)) |
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83 rnd = finv (rand (sz), m, n); |
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84 else |
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85 rnd = NaN * ones (sz); |
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86 endif |
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87 else |
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88 rnd = zeros (sz); |
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89 |
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90 k = find (!(m > 0) | !(m < Inf) | |
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91 !(n > 0) | !(n < Inf)); |
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92 if (any (k)) |
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93 rnd(k) = NaN; |
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94 endif |
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95 |
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96 k = find ((m > 0) & (m < Inf) & |
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97 (n > 0) & (n < Inf)); |
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98 if (any (k)) |
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99 rnd(k) = finv (rand (size (k)), m(k), n(k)); |
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100 endif |
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101 endif |
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102 |
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103 endfunction |
