Issue with exercice - GARCH Models

Hello guys !

I need your help for a small exercice with Matlab. I tried to do it but I'm blocked at this level :

data{1} = 'allianz.xlsx'; data{2} = 'delhaize.xlsx'; data{3} = 'microsoft.xlsx';

for m = 1:3

for i=xlsread(data{m})

    ri = price2ret(i);
    parami = garchpq(ri, 1, 1);
    omi = parami(1);
    ai = parami(2);
    bi = parami(3);
    v = omi/(1-ai-bi)
end

end

Could you please tell me if you think I've started right ? I've enclosed the needed data to pursue this exercice in an appropriate way.

I would be very happy if you look into this :-) !

Thank's!