You have to make vectors out of them, then it works:
f = @(x) x.^3+2; % Changed ‘inline’ To Anonymous Function
x1=2; x2=-2; x3=4;
[Fmin,ix] = min([f(x1),f(x2),f(x3)]); % Vector Of ‘f(x)’
x = [x1 x2 x3]; % Vector Of ‘x’
xFmin = x(ix) % ‘argmin’
