math Package

import "math"

// Returns the absolute value.
x := math.Abs(-3.14)   // 3.14

// Returns the square root.
s := math.Sqrt(9.0)    // 3.0

// Rounds down, rounds up, or rounds to the nearest integer.
f := math.Floor(3.7)   // 3.0
c := math.Ceil(3.2)    // 4.0
r := math.Round(3.5)   // 4.0

// Returns the larger or smaller of two values.
big := math.Max(5.0, 3.0)  // 5.0
small := math.Min(5.0, 3.0) // 3.0

// Uses mathematical constants.
pi := math.Pi    // 3.141592653589793
e  := math.E     // 2.718281828459045

package main

import (
    "fmt"
    "math"
)

func main() {
    // Examples of basic math functions.
    fmt.Println("--- Abs / Sqrt / Pow ---")
    fmt.Println("Abs(-7.5):", math.Abs(-7.5))
    fmt.Println("Sqrt(16):", math.Sqrt(16))
    fmt.Println("Pow(2, 10):", math.Pow(2, 10))   // 2 to the power of 10

    fmt.Println()

    // Comparing rounding methods.
    fmt.Println("--- Rounding ---")
    x := 3.567
    fmt.Printf("Original: %.3f\n", x)
    fmt.Printf("Floor: %.1f\n", math.Floor(x))   // round down
    fmt.Printf("Ceil:  %.1f\n", math.Ceil(x))    // round up
    fmt.Printf("Round: %.1f\n", math.Round(x))   // round to nearest

    fmt.Println()

    // Comparing max and min values.
    fmt.Println("--- Max / Min ---")
    fmt.Printf("Max(12.5, 7.3): %.1f\n", math.Max(12.5, 7.3))
    fmt.Printf("Min(12.5, 7.3): %.1f\n", math.Min(12.5, 7.3))

    fmt.Println()

    // Logarithmic and exponential functions.
    fmt.Println("--- Log / Exp ---")
    fmt.Printf("Log(math.E): %.4f\n", math.Log(math.E))  // natural log
    fmt.Printf("Log2(8): %.1f\n", math.Log2(8))           // base-2 log
    fmt.Printf("Log10(1000): %.1f\n", math.Log10(1000))   // common log
    fmt.Printf("Exp(1): %.6f\n", math.Exp(1))             // e^1

    fmt.Println()

    // Trigonometric functions (in radians).
    fmt.Println("--- Trigonometry ---")
    fmt.Printf("Sin(Pi/2): %.4f\n", math.Sin(math.Pi/2))  // 1.0
    fmt.Printf("Cos(Pi):   %.4f\n", math.Cos(math.Pi))    // -1.0

    fmt.Println()

    // Checking constants.
    fmt.Println("--- Constants ---")
    fmt.Printf("Pi: %.15f\n", math.Pi)
    fmt.Printf("E:  %.15f\n", math.E)
    fmt.Println("MaxFloat64:", math.MaxFloat64)
    fmt.Println("MaxInt:", math.MaxInt)
}

All functions in the math package accept and return float64 values. Integer arguments are converted automatically, but if you need the integer part of a result, cast it explicitly with int(math.Floor(x)).

Taking the square root of a negative number (math.Sqrt(-1)) returns NaN. Use math.IsNaN() to check for NaN values.

For random number generation, see the math/rand package.