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:
Computing Square Roots with Newton's Method
pages.mtu.edu › ~shene › COURSESThis program contains a function MySqrt () that uses Newton's ! method to find the square root of a positive number. This is ! an iterative method and the program keeps generating better ! approximation of the square root until two successive ! approximations have a distance less than the specified tolerance. !