Alpha max plus beta min algorithm

The alpha max plus beta min algorithm is a high-speed approximation of the square root of the sum of two squares. The square root of the sum of two squares, also known as Pythagorean addition, is a useful function, because it finds the hypotenuse of a right triangle given the two side lengths, the norm of a 2-D vector, or the magnitude | z | = a 2 + b 2 {\displaystyle |z|={\sqrt {a^{2}+b^{2}}}} of a complex number z = a + bi given the real and imaginary parts.

Source: Wikipedia — Alpha max plus beta min algorithm (CC BY-SA 4.0)