function giai_pt(hamso,pp,x0,ss)
    if (nargin < 4) || isempty(ss)
        ss=1e-5;
    end;
    switch (pp)
        case {'N','n','Newton','newton','t','tt','tieptuyen'}
            newton_tb(hamso,x0,ss);
        case {'S','s','Secant','secant','d','dc','daycung'}
            daycung_tb(hamso,x0,ss);
        case {'B','b','Bin','bin','Binary','binary','c','cd','chiadoi'}
            chiadoi_tb (hamso,x0,ss);
        case {'L','l','Lap','lap'}
            pplap_tb (hamso, x0, ss);
        otherwise
            disp 'Ban can chon phuong phap'
            disp 'Cac phuong phap ho tro:'
            disp 'Chia doi: B, b, Bin, bin, Binary, binary, c , cd, chiadoi'
    end
            