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: armaxfilter_likelihood.m
    path of file: ./repos/malini/Codes/FC_EC_calculation code/DynamicFC/jplv7/Ucsd_garch/Garch
    
    the code of the file until where you have to start completion: function [LLF, errors, likelihoods] = armaxfilter_likelihood(parameters , regressand , regressors, ar , ma, tau)
% PURPOSE:
%     This is the likelihood function for armaxfilter
% 

    
function [LLF, errors, likelihoods] = armaxfilter_likelihood(parameters , regressand , regressors, ar , ma, tau)
% PURPOSE:
%     This is the likelihood function for armaxfilter
% 
% USAGE:
%     [LLF, errors, likelihoods] = armaxfilter_likelihood(parameters , regressand , regressors, ar , ma, tau)
% 
% 
% INPUTS:
%     parameters:   A vector of GARCH process aprams of the form [constant, arch, garch]
%     regressand:   A set of zero mean residuals
%     regressors:   A matrix of exogenous(conditionally) of size (1+nlags+numX) by t with a ci
%     ar:           The AR order
%     ma:           The MA order of the ARMA process
%     tau:          Length(regressand+max(p,q))
% 
% OUTPUTS:
%     LLF:          Minus 1 times the log likelihood
%     errors:       Time series fo model erors
%     likelihoods:  Time series fo likelihoods
% 
% 
% COMMENTS:
% 
% Author: Kevin Sheppard
% kevin.sheppard@economics.ox.ac.uk
% Revision: 2    Date: 12/31/2001

if size(parameters,1)>size(parameters,2)
    parameters=parameters';
end