Newton's method - Wikipedia
https://en.wikipedia.org/wiki/Newton's_methodConsider the problem of finding the square root of a number a, that is to say the positive number x such that x = a. Newton's method is one of many methods of computing square roots. We can rephrase that as finding the zero of f(x) = x − a. We have f′(x) = 2x. For example, for finding the square root of 612 with an initial guess x0 = 10, the sequence given by Newton's method is:
Newton's method - Wikipedia
en.wikipedia.org › wiki › Newton&Given xn, define. x n + 1 = x n − f ( x n ) f ′ ( x n ) , {\displaystyle x_ {n+1}=x_ {n}- {\frac {f (x_ {n})} {f' (x_ {n})}},} which is just Newton's method as before. Then define. z n + 1 = z n − f ( z n ) f ′ ( x n ) , {\displaystyle z_ {n+1}=z_ {n}- {\frac {f (z_ {n})} {f' (x_ {n})}},}