Reference · Math

math.gcd

math.gcd(int | list...) -> int

What it does

The greatest common divisor of some ints, as Python's math.gcd: the largest int that divides each of them. The ints come as separate arguments or as one list; math.gcd(12, 18) and math.gcd([12, 18]) are both 6. The answer is never negative.

Examples

print(math.gcd(12, 18), math.gcd(12, 18, 30), math.gcd([12, 18, 30]))print(math.gcd(7, 13), math.gcd(-12, 18))

6 6 61 6

Edge cases

• Zero divides into anything: math.gcd(0, 5) is 5, and math.gcd(0, 0) is 0.
• One int gives its absolute value, and no ints at all (or an empty list) give 0, as in Python.
• Negative ints count by their absolute value: math.gcd(-4, -6) is 2.
• A float that is a whole number is accepted as an int.

print(math.gcd(0, 5), math.gcd(0, 0), math.gcd(7), math.gcd(), math.gcd([]))print(math.gcd(-4, -6), math.gcd(4, 6.0))

5 0 7 0 02 2

Errors

An argument that is not an int, or a list item that is not, is a runtime error, not an error value; a float with a fraction and null are refused. A list may only be the whole argument list: math.gcd(12, [18]) fails.

print(math.gcd(4, 6.5))

line 1: `math.gcd` expects an int as argument 2, got float

print(math.gcd(12, [18]))

line 1: `math.gcd` expects an int as argument 2, got list

Chaining

A list in a pipeline is the only argument, so xs | math.gcd reduces the whole list; a number in a pipeline is the first of two:

print([12, 18, 30] | math.gcd)print(12 | math.gcd(18))let [a, b] = [12, 18]let g = math.gcd(a, b)print(`${a / g}/${b / g}`)

662/3

See also

math.lcm, math.isqrt, math.factorial

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