% ASECH ASECH Inverse Hyperbolic Secant Function
% 
% Usage
% 
% Computes the inverse hyperbolic secant of its argument.  The general
% syntax for its use is
% 
%   y = asech(x)
% 
% where x is an n-dimensional array of numerical type.

function y = asech(x)
  if (nargin == 0 || ~isnumeric(x))
    error('asech expects a single, numeric input');
  end
  y = acosh(1.f./x);