function find_zero_poly_test(z20func)

cd(fileparts(which(mfilename)));

funcs = dir('find_zero_poly_test*.m');

x = -10:.1:10;

for i = 1:length(funcs)
    
    func = regexprep(funcs(i).name, '\.m$', '');
    fh   = str2func(func);
    
    if isempty(regexp(func, '\d+$', 'once')); continue; end;
    
    disp(func);
    
    b = [0 4];
    z = feval(fh, 0, b);
    
%     bn = [];
%     zn = [];
%     n  = 0;
%     c  = false;
    
    [bn zn n c] = feval(z20func, 0, b, z, 'zFunction', fh);
    
    bt = [b bn];
    zt = [z zn];
    
    figure; hold on;
    plot(x,feval(fh, 0, x),'-k');
    plot(b,z,'og');
    plot(bn,zn,'or');
    
    if c; plot(bt(end),zt(end),'*b'); end;
    
    title(sprintf('%s (%d)', func, n), 'Interpreter', 'none');
    grid on;
    
end