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: com_size.m
    path of file: ./repos/malini/Codes/FC_EC_calculation code/DynamicFC/jplv7/distrib
    
    the code of the file until where you have to start completion: function [ret, x, aout, bout] = com_size(x,a,b)
% PURPOSE: makes a,b scalars equal to constant matrices size(x)
%          or leaves them alone if they are already common_size
%--------------------------------------------------------------
% USAGE: [ret x aout bout] = com_size(x,a,b)
% where: x = a matrix or vector
%        a = a scalar or matrix
%        b = a scalar or matrix
%--------------------------------------------------------------

    
function [ret, x, aout, bout] = com_size(x,a,b)
% PURPOSE: makes a,b scalars equal to constant matrices size(x)
%          or leaves them alone if they are already common_size
%--------------------------------------------------------------
% USAGE: [ret x aout bout] = com_size(x,a,b)
% where: x = a matrix or vector
%        a = a scalar or matrix
%        b = a scalar or matrix
%--------------------------------------------------------------
% RETURNS:
%        ret = an indicator 0 if common_size, 1 if not
%        x   = input matrix
%        a   = matrix size(x) or input matrix a if already size(x)
%        b   = matrix size(x) or input matrix b if already size(x)
%--------------------------------------------------------------

% written by:
% James P. LeSage, Dept of Economics
% University of Toledo
% 2801 W. Bancroft St,
% Toledo, OH 43606
% jlesage@spatial-econometrics.com

if nargin ~= 3
error('Wrong # of arguments to com_size');
end