linguistic:paraphrasing, structural:summarization
Other methods

If a and b are both nonzero, the greatest common divisor of a and b can be computed by using least common multiple (LCM) of a and b:

but more commonly the LCM is computed from the GCD.

Using Thomae's function f,

which generalizes to a and b rational numbers or commensurable real numbers.

Keith Slavin has shown that for odd a ≥ 1:

which is a function that can be evaluated for complex b. Wolfgang Schramm has shown that

is an entire function in the variable b for all positive integers a where c (k) is Ramanujan's sum.