This could work for approximations. But if you want the exact value, this might not be super effective, as there are values without closed forms (that is to say

This could work for approximations. But if you want the exact value, this might not be super effective, as there are values without closed forms (that is to say, that are not expressible simply with the *-+/ and sqrt/log and other usual operations). So your iteration procedure will probably get to a good approximation, but might not find the "core" expression.