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1 ## Copyright (C) 2006 David Bateman <dbateman@free.fr> |
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2 ## |
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3 ## This program is free software; you can redistribute it and/or modify |
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4 ## it under the terms of the GNU General Public License as published by |
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5 ## the Free Software Foundation; either version 2 of the License, or |
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6 ## (at your option) any later version. |
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7 ## |
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8 ## This program is distributed in the hope that it will be useful, |
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9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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11 ## GNU General Public License for more details. |
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12 ## |
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13 ## You should have received a copy of the GNU General Public License |
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14 ## along with this program; if not, write to the Free Software |
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15 ## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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16 |
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17 ## -*- texinfo -*- |
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18 ## @deftypefn {Function File} {} tand (@var{x}) |
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19 ## Compute the tangent of an angle in degrees. Returns zero for elements |
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20 ## of for which @code{@var{x}/180} is an integer and @code{Inf} for elements |
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21 ## where @code{(@var{x}-90}/180} is an integer. |
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22 ## @seealso{tan, cosd, sind, acosd, asind, atand} |
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23 ## @end deftypefn |
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24 |
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25 function y = tand (x) |
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26 if (nargin != 1) |
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27 print_usage (); |
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28 endif |
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29 I0 = x / 180; |
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30 I90 = (x-90) / 180; |
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31 y = tan (I0 .* pi); |
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32 y(I0 == round (I0) & finite (I0)) = 0; |
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33 y(I90 == round (I90) & finite (I90)) = Inf; |
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34 endfunction; |
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35 |
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36 %!error(tand()) |
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37 %!error(tand(1,2)) |
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38 %!assert(tand(10:10:80),tan(pi*[10:10:80]/180),-10*eps) |
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39 %!assert(tand([0,180,360]) == 0) |
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40 %!assert(tand([90,270]) == Inf) |
