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1 ## Copyright (C) 1993, 1994, 1995, 1996, 1997, 1999, 2000, 2004, 2005, |
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2 ## 2006, 2007 John W. Eaton |
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3 ## |
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4 ## This file is part of Octave. |
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5 ## |
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6 ## Octave is free software; you can redistribute it and/or modify it |
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7 ## under the terms of the GNU General Public License as published by |
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8 ## the Free Software Foundation; either version 3 of the License, or (at |
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9 ## your option) any later version. |
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10 ## |
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11 ## Octave is distributed in the hope that it will be useful, but |
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12 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 ## General Public License for more details. |
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15 ## |
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16 ## You should have received a copy of the GNU General Public License |
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17 ## along with Octave; see the file COPYING. If not, see |
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18 ## <http://www.gnu.org/licenses/>. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} rot90 (@var{x}, @var{n}) |
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22 ## Return a copy of @var{x} with the elements rotated counterclockwise in |
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23 ## 90-degree increments. The second argument is optional, and specifies |
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24 ## how many 90-degree rotations are to be applied (the default value is 1). |
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25 ## Negative values of @var{n} rotate the matrix in a clockwise direction. |
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26 ## For example, |
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27 ## |
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28 ## @example |
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29 ## @group |
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30 ## rot90 ([1, 2; 3, 4], -1) |
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31 ## @result{} 3 1 |
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32 ## 4 2 |
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33 ## @end group |
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34 ## @end example |
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35 ## |
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36 ## @noindent |
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37 ## rotates the given matrix clockwise by 90 degrees. The following are all |
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38 ## equivalent statements: |
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39 ## |
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40 ## @example |
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41 ## @group |
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42 ## rot90 ([1, 2; 3, 4], -1) |
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43 ## rot90 ([1, 2; 3, 4], 3) |
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44 ## rot90 ([1, 2; 3, 4], 7) |
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45 ## @end group |
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46 ## @end example |
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47 ## |
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48 ## Due to the difficulty of defining an axis about which to rotate the |
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49 ## matrix @code{rot90} only work with 2-D arrays. To rotate N-d arrays |
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50 ## use @code{rotdim} instead. |
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51 ## @seealso{rotdim, flipud, fliplr, flipdim} |
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52 ## @end deftypefn |
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53 |
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54 ## Author: jwe |
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55 |
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56 function y = rot90 (x, k) |
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57 |
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58 if (nargin == 1 || nargin == 2) |
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59 if (nargin < 2) |
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60 k = 1; |
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61 endif |
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62 |
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63 if (ndims (x) > 2) |
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64 error ("rot90: Only works with 2-D arrays") |
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65 endif |
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66 |
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67 if (imag (k) != 0 || fix (k) != k) |
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68 error ("rot90: k must be an integer"); |
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69 endif |
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70 |
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71 k = rem (k, 4); |
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72 |
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73 if (k < 0) |
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74 k = k + 4; |
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75 endif |
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76 |
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77 if (k == 0) |
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78 y = x; |
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79 elseif (k == 1) |
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80 y = flipud (x.'); |
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81 elseif (k == 2) |
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82 y = flipud (fliplr (x)); |
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83 elseif (k == 3) |
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84 y = (flipud (x)).'; |
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85 else |
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86 error ("rot90: internal error!"); |
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87 endif |
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88 else |
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89 print_usage (); |
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90 endif |
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91 |
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92 endfunction |
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93 |
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94 %!test |
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95 %! x1 = [1, 2; |
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96 %! 3, 4]; |
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97 %! x2 = [2, 4; |
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98 %! 1, 3]; |
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99 %! x3 = [4, 3; |
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100 %! 2, 1]; |
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101 %! x4 = [3, 1; |
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102 %! 4, 2]; |
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103 %! |
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104 %! assert((rot90 (x1)== x2 && rot90 (x1, 2) == x3 && rot90 (x1, 3) == x4 |
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105 %! && rot90 (x1, 4) == x1 && rot90 (x1, 5) == x2 && rot90 (x1, -1) == x4)); |
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106 |
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107 %!error rot90 (); |
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108 |
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109 %!error rot90 (1, 2, 3); |
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110 |
