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1 ## Copyright (C) 2006 David Bateman <dbateman@free.fr> |
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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} {} cosd (@var{x}) |
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21 ## Compute the cosine of an angle in degrees. Returns zero in elements |
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22 ## for which @code{(@var{x}-90)/180} is an integer. |
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23 ## @seealso{cos, sind, tand, acosd, asind, atand} |
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24 ## @end deftypefn |
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25 |
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26 function y = cosd (x) |
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27 if (nargin != 1) |
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28 print_usage (); |
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29 endif |
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30 I = x / 180; |
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31 y = cos (I .* pi); |
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32 I = I + 0.5; |
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33 y(I == round (I) & finite (I)) = 0; |
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34 endfunction |
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35 |
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36 %!error(cosd()) |
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37 %!error(cosd(1,2)) |
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38 %!assert(cosd(0:10:80),cos(pi*[0:10:80]/180),-10*eps) |
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39 %!assert(cosd([0,180,360]) != 0) |
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40 %!assert(cosd([90,270]) == 0) |
