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## -*- texinfo -*-
## @deftypefn {} {@var{y} =} 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

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) & isfinite (I0)) = 0;
  y(I90 == fix (I90) & isfinite (I90)) = Inf;

endfunction


%!assert (tand (10:10:80), tan (pi*[10:10:80]/180), -10*eps)
%!assert (tand ([0, 180, 360]) == 0)
%!assert (tand ([90, 270]) == Inf)

%!error <Invalid call> tand ()