update packages

[CreaPhase.git] / octave_packages / m / elfun / tand.m

diff --git a/octave_packages/m/elfun/tand.m b/octave_packages/m/elfun/tand.m
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+## Copyright (C) 2006-2012 David Bateman
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or (at
+## your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} tand (@var{x})
+## Compute the tangent for each element of @var{x} in degrees.  Returns zero
+## for elements where @code{@var{x}/180} is an integer and @code{Inf} for
+## elements where @code{(@var{x}-90)/180} is an integer.
+## @seealso{atand, tan}
+## @end deftypefn
+
+## Author: David Bateman <dbateman@free.fr>
+
+function y = tand (x)
+  if (nargin != 1)
+    print_usage ();
+  endif
+  I0 = x / 180;
+  I90 = (x-90) / 180;
+  y = tan (I0 .* pi);
+  y(I0 == fix (I0) & finite (I0)) = 0;
+  y(I90 == fix (I90) & finite (I90)) = Inf;
+endfunction;
+
+%!error(tand())
+%!error(tand(1,2))
+%!assert(tand(10:10:80),tan(pi*[10:10:80]/180),-10*eps)
+%!assert(tand([0,180,360]) == 0)
+%!assert(tand([90,270]) == Inf)