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1 ## Copyright (C) 1999, 2000 Paul Kienzle |
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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 {Mapping Function} {} mod (@var{x}, @var{y}) |
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22 ## Compute modulo function, using |
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23 ## |
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24 ## @example |
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25 ## x - y .* floor (x ./ y) |
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26 ## @end example |
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27 ## |
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28 ## Note that this handles negative numbers correctly: |
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29 ## @code{mod (-1, 3)} is 2, not -1 as @code{rem (-1, 3)} returns. |
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30 ## Also, @code{mod (@var{x}, 0)} returns @var{x}. |
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31 ## |
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32 ## An error message is printed if the dimensions of the arguments do not |
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33 ## agree, or if either of the arguments is complex. |
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34 ## @seealso{rem, round} |
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35 ## @end deftypefn |
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36 |
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37 ## Author: Paul Kienzle <pkienzle@kienzle.powernet.co.uk> |
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38 ## Modified by: Teemu Ikonen <tpikonen@pcu.helsinki.fi> |
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39 ## Adapted by: jwe |
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40 |
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41 function r = mod (x, y) |
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42 |
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43 if (nargin != 2) |
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44 usage ("r = mod (x, y)"); |
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45 endif |
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46 |
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47 if (((ndims (x) != ndims (y)) || any (size (x) != size (y))) && |
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48 ! (isscalar (x) || isscalar (y))) |
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49 error ("mod: argument sizes must agree"); |
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50 endif |
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51 |
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52 ## Matlab allows complex arguments, but as far as I can tell, that's a |
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53 ## bunch of hooey. |
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54 |
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55 if (isreal (x) && isreal (y)) |
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56 nz = y != 0.0; |
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57 if (all (nz(:))) |
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58 ## No elements of y are zero. |
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59 r = x - y .* floor (x ./ y); |
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60 elseif (isscalar (y)) |
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61 ## y must be zero. |
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62 r = x; |
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63 else |
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64 ## Some elements of y are zero. |
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65 if (isscalar (x)) |
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66 r = x * ones (size (y)); |
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67 else |
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68 r = x; |
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69 x = x(nz); |
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70 endif |
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71 y = y(nz); |
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72 r(nz) = x - y .* floor (x ./ y); |
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73 endif |
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74 else |
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75 error ("mod: complex arguments are not allowed"); |
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76 endif |
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77 |
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78 endfunction |
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79 |
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80 ## empty input test |
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81 %!assert (isempty(mod([], []))); |
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82 |
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83 ## x mod y, y != 0 tests |
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84 %!assert (mod(5, 3), 2); |
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85 %!assert (mod(-5, 3), 1); |
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86 %!assert (mod(0, 3), 0); |
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87 %!assert (mod([-5, 5, 0], [3, 3, 3]), [1, 2, 0]); |
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88 %!assert (mod([-5; 5; 0], [3; 3; 3]), [1; 2; 0]); |
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89 %!assert (mod([-5, 5; 0, 3], [3, 3 ; 3, 1]), [1, 2 ; 0, 0]); |
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90 |
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91 ## x mod 0 tests |
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92 %!assert (mod(5, 0), 5); |
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93 %!assert (mod(-5, 0), -5); |
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94 %!assert (mod([-5, 5, 0], [3, 0, 3]), [1, 5, 0]); |
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95 %!assert (mod([-5; 5; 0], [3; 0; 3]), [1; 5; 0]); |
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96 %!assert (mod([-5, 5; 0, 3], [3, 0 ; 3, 1]), [1, 5 ; 0, 0]); |
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97 %!assert (mod([-5, 5; 0, 3], [0, 0 ; 0, 0]), [-5, 5; 0, 3]); |
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98 |
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99 ## mixed scalar/matrix tests |
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100 %!assert (mod([-5, 5; 0, 3], 0), [-5, 5; 0, 3]); |
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101 %!assert (mod([-5, 5; 0, 3], 3), [1, 2; 0, 0]); |
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102 %!assert (mod(-5,[0,0; 0,0]), [-5, -5; -5, -5]); |
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103 %!assert (mod(-5,[3,0; 3,1]), [1, -5; 1, 0]); |
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104 %!assert (mod(-5,[3,2; 3,1]), [1, 1; 1, 0]); |
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105 |
