You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: trev.m
    path of file: ./repos/hctsa/Toolboxes/OpenTSTOOL/tstoolbox/@signal
    
    the code of the file until where you have to start completion: function rs=trev(s,tau,ntests,method)

%tstoolbox/@signal/trev
%   Syntax:
%     * rs = trev(s,tau,n,method)
%
%   Input Arguments:
%     * tau - see explaination below

    
function rs=trev(s,tau,ntests,method)

%tstoolbox/@signal/trev
%   Syntax:
%     * rs = trev(s,tau,n,method)
%
%   Input Arguments:
%     * tau - see explaination below
%     * n - number of surrogate data sets to generate
%     * method - method to generate the surrogate data sets:
%          + 1: surrogate1
%          + 2: surrogate2
%          + 3: surrogate3
%
%   Output Arguments:
%     * rs is a row vector, returned as signal object. The first item is
%       the T[REV] value for the original data set s. The following n
%       values are the T[REV] values for the generated surrogates. There
%       exist a special plothint ('surrbar') for the view function to show
%       this kind of result in the common way.
%
%   This function calculates a special value for the original data set and
%   the n generated surrogate data sets. The T[REV] value is defined as
%   followed:
%
%               [missing equation, see html/pdf documentation]
%
%   In terms of surrogate data test this is a test statistics for time
%   reversibility. The original trev function is located under
%   utils/trev.m and use simple matlab vectors.
%
% Copyright 1997-2001 DPI Goettingen, License http://www.physik3.gwdg.de/tstool/gpl.txt

%x1=data(cut(s,1,1+tau,length(data(s))))';


x = [trev(data(cut(s,1,1,length(data(s))))',tau)];

  
for tests=1:ntests
  switch(method)
   case 1
    a=surrogate1(s);
   case 2
    a=surrogate2(s);
   case 3
    a=surrogate3(s);
   otherwise
    a=surrogate1(s);
  end