function f = svmexample_f(x);
    x1=x(1); x2=x(2); x3=x(3);
    f=-(x1+x2+x3-(0.5*x1^2+2*x2^2+4.5*x3^2-2*x1*x2-3*x1*x3+6*x2*x3));
    return