function []=mcompare(s1,s2)
// MCOMPARE : MCOMPARE ( [ 'file1' ; 'file2' ] , [ 'var1' ; 'var2' ...] ) 
// Copyright (C) 2001 Michel Juillard
// 
//  This optional command plots the relative differences between
//  two different simulations for a list of variables. One plot 
//  is drawn for each variable. The trajectories must have been
//  previously saved by the instruction DYNASAVE. The simulation
//  in file1 serves as the base simulation and the ploted quantity
//  is equal to the difference between the two simulation reported
//  to the first one. If, for a given variable, zero is one of the
//  value of the base simulation, the absolute difference is ploted
//  instead of the relative one.
 
global('dsmpl_','iter_');
global('nvx','nvy','x','y','lag1');
 
ftest(s1,s2);
 
ix = (1-lag1(1):size(x,2)-lag1(1))';
i = (lag1(1):size(ix,1)-lag1(2)+1)';
 
if size(dsmpl_,1)==1 then
  error('DSAMPLE not specified.');
end
 
if dsmpl_(3)>0 then
  if dsmpl_(3)==2 then
    if dsmpl_(1)<0|dsmpl_(2)>(size(x,2)-lag1(2)) then
      error('Wrong sample.');
    end
    i = (dsmpl_(1)+lag1(1):dsmpl_(2)+lag1(1))';
  elseif dsmpl_(3)==1 then
    if dsmpl_(1)>(size(x,2)-lag1(2)) then
      error('Wrong sample.');
    end
    i = (lag1(1):dsmpl_(1)+lag1(1))';
  end
end
 
for k = 1:size(x,1)
  xset('window',max(winsid()+1))
  max(winsid());
  x1 = x(k,i);
  y1 = y(k,i);
   
  //! unknown arg type, using mtlb_length 
  if nnz(x1)<mtlb_length(x1) then
    mtlb_plot(ix(i),y1-x1);
  else
    mtlb_plot(ix(i),(y1-x1) ./ x1);
  end
  xtitle(' ','Periods',' ');
  xtitle('Variable '+s2(k),' ',' ');
end
 
return