% COTD COTD Cotangent Degrees Function
% 
% Usage
% 
% Computes the cotangent of the argument, but takes
% the argument in degrees instead of radians (as is the case
% for cot). The syntax for its use is
% 
%    y = cotd(x)
% 
function y = cotd(x)
  if (nargin == 0 || ~isnumeric(x) || ~isreal(x))
    error('cotd expects a real numeric input');
  end
  y = cot(deg2rad(x));
