Reference · Math

math.remainder

math.remainder(num, num) -> float

What it does

The IEEE remainder: the first number minus the multiple of the second that is closest to it, as a float, as Python's math.remainder. The result lies between -|y| / 2 and |y| / 2, so it can be negative for positive arguments: math.remainder(8, 3) is -1.0, since 8 is closer to 9 than to 6. For the remainder with the dividend's sign use math.fmod or %.

Examples

print(math.remainder(7, 3), math.remainder(8, 3), math.remainder(7.5, 2))print(math.fmod(8, 3), 8 % 3)

1.0 -1.0 -0.52.0 2

Edge cases

• A tie goes to the even multiple: math.remainder(7, 2) is -1.0 (7 is as close to 8 as to 6, and 8 is 4 × 2) while math.remainder(9, 2) is 1.0.
• The sign of the result is not the dividend's: math.remainder(-5.5, 1) is 0.5.
• An infinite divisor leaves the number as it is.
• -0.0 keeps its sign, and NaN in either place gives NaN.

print(math.remainder(7, 2), math.remainder(9, 2), math.remainder(-5.5, 1))print(math.remainder(7, float("inf")), math.remainder(-0.0, 3), math.remainder(float("nan"), 2))

-1.0 1.0 0.57.0 -0.0 NaN

Errors

A divisor of zero, or an infinite dividend, is a runtime error, math domain error, not an error value. An argument that is not a number is a runtime error as well.

print(math.remainder(7, 0))

line 1: `math.remainder`: math domain error (7, 0)

print(math.remainder(float("inf"), 3))

line 1: `math.remainder`: math domain error (inf, 3)

Chaining

In a pipeline the dividend comes first. The distance from the nearest multiple is its absolute value:

print(8 | math.remainder(3))print([7, 8, 9] | map((x) => math.remainder(x, 3)) | map(math.fabs))

-1.0[1.0, 1.0, 0.0]

See also

math.fmod, math.fabs, round

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