Result	Iteration formula
1/b:	x' = x * (2 - b*x)
1/sqrt(b):	x' = 0.5 * x * (3 - b*x²)

Use the exact values for 1/x and 1/sqrt(x) displayed in the bottom textfields to compare the iterated values with the exact values, or to find a suitable start value for the iteration. For example, try the x value 3.14159265 and the initial values 0.02, 0.2, 0.3 and compare how fast the iteration converges.

Note that the iterations converge only in a small region near the correct result value. In the AMD K6 and Athlon processors, special lookup-tables and logic provide an initial value of sufficient precision (about 14 bits).