Thus，for instance，it may come as a shock to mathematicians to learn that the Schrodinger equation for the hydrogen atom is not a literally correct description of this atom，but only an approximation to a somewhat more correct equation taking account of spin，magnetic dipole，and relativistic effects;and that this corrected equation is itself only an imperfect approximation to an infinite set of quantum field-theoretical equations.
因此，舉例來說，對數(shù)學(xué)家而言，了解到下述情形可能會令其驚愕不已，即薛定諤(Schrodinger)的氫原子方程式并非是對該原子作出的一種絕然正確的描述，而僅僅是個近似值，趨近于一個在某種程度上更為正確的將自旋、磁性偶極子、以及相對論效應(yīng)考慮在內(nèi)的方程式;而這個得以糾正的方程式就其本身而言也只是一個不完美的近似值，趨近于無窮無盡的一整套量子場論方程式。