std.math

Numeric constants and helpers that aren’t idiomatic as methods.

The core math operations — abs, sqrt, sin, cos, tan, floor, ceil, round, pow, log, exp, min, max — are methods on numbers, not stdlib functions. They live in core because they wrap f64::* operations that Bop can’t implement itself.

Import

use std.math                           // glob
use std.math.{PI, clamp}               // selective
use std.math as m                      // aliased

Constants

All three are const (all-caps name, value is fixed at module load).

Functions

clamp(x, lo, hi)

Clamp x into the range [lo, hi]. Works on any mix of int and number; the return type mirrors the widest input.

use std.math.{clamp}
print(clamp(5, 0, 10))     // 5
print(clamp(-3, 0, 10))    // 0
print(clamp(42, 0, 10))    // 10

sign(x)

Returns -1, 0, or 1. Works on both int and number.

use std.math.{sign}
print(sign(-7))       // -1
print(sign(0))        // 0
print(sign(3.14))     // 1

factorial(n)

n! using iterative multiplication. Raises an integer-overflow error for n ≥ 21 (the smallest factorial that doesn’t fit in i64). Negative n returns 0.

use std.math.{factorial}
print(factorial(5))    // 120
print(factorial(10))   // 3628800

gcd(a, b)

Greatest common divisor using the Euclidean algorithm. Handles negatives by taking absolute values. gcd(0, 0) returns 0.

use std.math.{gcd}
print(gcd(12, 18))    // 6
print(gcd(-15, 25))   // 5

lcm(a, b)

Least common multiple. lcm(0, x) is 0 (so callers don’t have to special-case).

use std.math.{lcm}
print(lcm(4, 6))     // 12
print(lcm(0, 9))     // 0

mean(arr)

Arithmetic mean of a numeric array. Raises on an empty array so callers notice rather than silently getting 0.

use std.math.{mean}
print(mean([1, 2, 3, 4]))     // 2.5
print(mean([10.0, 20.0]))     // 15

Need the sum or product instead? Use std.iter.sum / std.iter.product.