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: sar_panel_RE.m
    path of file: ./repos/malini/Codes/FC_EC_calculation code/DynamicFC/jplv7/spatial/panel
    
    the code of the file until where you have to start completion: function results = sar_panel_RE(y,x,W,T,info)
% PURPOSE: computes spatial lag model estimates for spatial panels 
%          (N regions*T time periods) with spatial random effects (u) 
%          y = p*W*y + X*b + u + e, using sparse matrix algorithms
% Supply data sorted first by time and then by spatial units, so first region 1,
% region 2, et cetera, in the first year, then region 1, region 2, et
% cetera in the second year, and so on
% ---------------------------------------------------
%  USAGE: results = sar_panel_RE(y,x,W,T,info)
%  where:  y = dependent variable vector
%          x = independent variables matrix
%          W = spatial weights matrix (standardized)
%          T = number of points in time
%       info = an (optional) structure variable with input options:
%       info.Nhes  = N =< Nhes asymptotic variance matrix is computed using analytical formulas,
%                    N > Nhes asymptotic variance matrix is c
    
function calls to save time)
% --------------------------------------------------
%  NOTES: if you use lflag = 1 or 2, info.rmin will be set = -1 
%                                    info.rmax will be set = 1
%         For number of spatial units < 500 you should use lflag = 0 to get
%         exact results, 
% ---------------------------------------------------
%
% Updated by: J.Paul Elhorst summer 2008
% University of Groningen
% Department of Economics
% 9700AV Groningen
% the Netherlands
% j.p.elhorst@rug.nl
%
% REFERENCES: 
% Elhorst JP (2003) Specification and Estimation of Spatial Panel Data Models,
% International Regional Science Review 26: 244-268.
% Elhorst JP (2009) Spatial Panel Data Models. In Fischer MM, Getis A (Eds.) 
% Handbook of Applied Spatial Analysis, Ch. C.2. Springer: Berlin Heidelberg New York.

time1 = 0; 
time2 = 0;
time3 = 0;
time4 = 0;

timet = clock; % start the clock for overall timing

W=sparse(W);

% if we have no options, invoke defaults
if nargin == 4
    info.lflag = 1;
    info.Nhes=500;
    fprintf(1,'default: pooled model without fixed effects \n');
end