function data = rrgen(tmax, Pe, Pn, seed, filename)
% data = rrgen(tmax, Pe, Pn, seed, 'filename');
%	OVERVIEW:
%       generates artificial rr time series over a time tmax seconds
%       and dumps the output to 'filename'. If filename is not specified,
%       the output is returned into the data array. If it is specified, then the
%       data array is zero-valued and of length(tmax). Pe and Pn are the 
%       probability of ectopy and noise.
%       Defaults :  tmax=300; 
%                   P(ectopy), Pe = 0.0003;  Probability of ectopy ~ 1 per hr 
%                   P(noise),  Pn = 0.0048;  Probability of noise ~ 16 per hr 
%                   P(noise) in sleep is Pn/12, P(ectopy) in sleep is unchanged. 
%                   seed=1;  
%       Requires rrgen binary - compilation of rrgenV3.c on your system:
%       1.  Compile RRGEN
%           Navigate to RRGEN in HRV Toolbox & Compile using gcc
%           gcc -Wall rrgenV3.c -lm -o rrgen
%               or
%           gcc -Wall -o rrgenV3 rrgenV3.c 
%       2.  Ensure executable is on the system path, or move executable to
%           usr/local/bin or similar location on the path
%       3.  Ensure executable is on Matlab's path using the addpath fn
%   INPUT:
%       tmax, Pe, Pn, seed - Described above
%       filename - string
%   OUTPUT:
%       data - RR intervals 
%   DEPENDENCIES & LIBRARIES:
%   REFERENCE: http://cinc.mit.edu/archives/2002/pdf/225.pdf
%       McSharry P.E., Clifford G.D., Tarassenko L., Smith L.: Method for 
%       generating an artificial RR tachogram of a typical healthy
%       human over 24-hours, Computers in Cardiology, 29:225-228, IEEE 
%       Computer Society Press, September 2002. 
%	REPO:       
%       https://github.com/cliffordlab/hrv_toolbox
%   ORIGINAL SOURCE AND AUTHORS:     
%       (C) P.E. McSharry & G.D. Clifford 2002 under the 
%       GNU Public License. Contact P. McSharry (patrick@mcsharry.net) 
%       or G. Clifford (gari@mit.edu)
%   LICENSE:    
%       This software is offered freely and without warranty under 
%       the GNU (v3 or later) public license. See license file for
%       more information
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
if nargin < 5
  filename = 'tmp.dat';
end
if nargin < 4
  seed=1;    
end
if nargin < 3
    Pn=0.0048;
end
if nargin < 2
    Pe=0.0003;
end
if nargin < 1
  tmax=300;
end

if tmax<115
    fprintf('Warning, tmax minimum value is 115, using this as default\n')    
end

tmax=round(tmax);
eval(['!rrgenV3 ' int2str(seed) ' ' int2str(tmax) ' ' int2str(Pe) ' ' int2str(Pn) ' > ' filename]);
fid = fopen(filename,'r');
data = fscanf(fid,'%f'); 
fclose(fid);

% if not file name read in from tmp.dat and then delete it.
if nargin < 5
 load tmp.dat;
 data = tmp;
 if(ispc==1)
  system('del tmp.dat');
 else
  system('rm tmp.dat');
 end
end