I’m not sure what context that link is assuming, but in an analysis context I typically see little o used in ways like e.g. “f(x)=f(x0)+dfdx|x0dx+o(dx2)”. The interpretation is that, as dx goes to 0, the o(dx2) terms all fall to zero at least quadratically (i.e. there is some C such that Cdx2 upper bounds the o(dx2) term once dx is sufficiently small). Usually I see engineers and physicists using this sort of notation when taking linear or quadratic approximations, e.g. for designing numerical algorithms.
Little o is just a tighter bound. I don’t know what you are referring to by your statement:
I’m not sure what context that link is assuming, but in an analysis context I typically see little o used in ways like e.g. “f(x)=f(x0)+dfdx|x0dx+o(dx2)”. The interpretation is that, as dx goes to 0, the o(dx2) terms all fall to zero at least quadratically (i.e. there is some C such that Cdx2 upper bounds the o(dx2) term once dx is sufficiently small). Usually I see engineers and physicists using this sort of notation when taking linear or quadratic approximations, e.g. for designing numerical algorithms.