math

Before You Start

• Applies to: Go 1.21+ (examples verified with Go 1.22) · Prerequisites: Base: Data Types · Read time: about 10 min

math is the basic mathematical operation library in Go, and it is a library that must be mastered and used proficiently.

Integer Constants

const (
   intSize = 32 << (^uint(0) >> 63) // 32 or 64

   MaxInt    = 1<<(intSize-1) - 1
   MinInt    = -1 << (intSize - 1)
   MaxInt8   = 1<<7 - 1
   MinInt8   = -1 << 7
   MaxInt16  = 1<<15 - 1
   MinInt16  = -1 << 15
   MaxInt32  = 1<<31 - 1
   MinInt32  = -1 << 31
   MaxInt64  = 1<<63 - 1
   MinInt64  = -1 << 63
   MaxUint   = 1<<intSize - 1
   MaxUint8  = 1<<8 - 1
   MaxUint16 = 1<<16 - 1
   MaxUint32 = 1<<32 - 1
   MaxUint64 = 1<<64 - 1
)

Floating Point Constants

const (
   MaxFloat32             = 0x1p127 * (1 + (1 - 0x1p-23)) // 3.40282346638528859811704183484516925440e+38
   SmallestNonzeroFloat32 = 0x1p-126 * 0x1p-23            // 1.401298464324817070923729583289916131280e-45

   MaxFloat64             = 0x1p1023 * (1 + (1 - 0x1p-52)) // 1.79769313486231570814527423731704356798070e+308
   SmallestNonzeroFloat64 = 0x1p-1022 * 0x1p-52            // 4.9406564584124654417656879286822137236505980e-324
)

Mathematical Constants

const (
   E   = 2.71828182845904523536028747135266249775724709369995957496696763 // https://oeis.org/A001113
   Pi  = 3.14159265358979323846264338327950288419716939937510582097494459 // https://oeis.org/A000796
   Phi = 1.61803398874989484820458683436563811772030917980576286213544862 // https://oeis.org/A001622

   Sqrt2   = 1.41421356237309504880168872420969807856967187537694807317667974 // https://oeis.org/A002193
   SqrtE   = 1.64872127070012814684865078781416357165377610071014801157507931 // https://oeis.org/A019774
   SqrtPi  = 1.77245385090551602729816748334114518279754945612238712821380779 // https://oeis.org/A002161
   SqrtPhi = 1.27201964951406896425242246173749149171560804184009624861664038 // https://oeis.org/A139339

   Ln2    = 0.693147180559945309417232121458176568075500134360255254120680009 // https://oeis.org/A002162
   Log2E  = 1 / Ln2
   Ln10   = 2.30258509299404568401799145468436420760110148862877297603332790 // https://oeis.org/A002392
   Log10E = 1 / Ln10
)

Maximum Value

func TestMax(t *testing.T) {
  fmt.Println(math.Max(1.0, 2.0))
}

=== RUN   TestMax
2
--- PASS: TestMax (0.00s)
PASS

Minimum Value

func TestMin(t *testing.T) {
   fmt.Println(math.Min(1.0, 2.0))
}

=== RUN   TestMin
1
--- PASS: TestMin (0.00s)
PASS

Absolute Value

func TestAbs(t *testing.T) {
   fmt.Println(math.Abs(-1))
}

=== RUN   TestAbs
1
--- PASS: TestAbs (0.00s)
PASS

Remainder

func TestMod(t *testing.T) {
   fmt.Println(math.Mod(1, 10))
   fmt.Println(math.Mod(12, 10))
}

=== RUN   TestMod
1
2
--- PASS: TestMod (0.00s)
PASS

NaN Detection

func TestName(t *testing.T) {
   fmt.Println(math.IsNaN(math.NaN()))
}

=== RUN   TestFloor
2
--- PASS: TestFloor (0.00s)
PASS

Inf Detection

func TestInf(t *testing.T) {
   fmt.Println(math.IsInf(1.0, 1))
   fmt.Println(math.IsInf(math.Inf(-1), -1))
}

=== RUN   TestInf
false
true
--- PASS: TestInf (0.00s)
PASS

Truncate

func TestTrunc(t *testing.T) {
   fmt.Println(math.Trunc(1.26))
   fmt.Println(math.Trunc(2.3333))
}

=== RUN   TestTrunc
1
2
--- PASS: TestTrunc (0.00s)
PASS

Floor

func TestFloor(t *testing.T) {
   fmt.Println(math.Floor(2.5))
}

=== RUN   TestFloor
2
--- PASS: TestFloor (0.00s)
PASS

Ceiling

func TestCeil(t *testing.T) {
   fmt.Println(math.Ceil(2.5))
}

=== RUN   TestCeil
3
--- PASS: TestCeil (0.00s)
PASS

Round

func TestRound(t *testing.T) {
   fmt.Println(math.Round(1.2389))
   fmt.Println(math.Round(-5.2389))
}

=== RUN   TestRound
1
-5
--- PASS: TestRound (0.00s)
PASS

Logarithm

func TestLog(t *testing.T) {
   fmt.Println(math.Log(100) / math.Log(10))
   fmt.Println(math.Log(1) / math.Log(2))
}

=== RUN   TestLog
2
0
--- PASS: TestLog (0.00s)
PASS

E Exponent

func TestEx(t *testing.T) {
   fmt.Println(math.Exp(2))
}

=== RUN   TestEx
7.38905609893065
--- PASS: TestEx (0.00s)
PASS

Power

func TestPow(t *testing.T) {
   fmt.Println(math.Pow(2, 3))
   fmt.Println(math.Pow(3, 3))
}

=== RUN   TestPow
8
27
--- PASS: TestPow (0.00s)
PASS

Square Root

func TestSqrt(t *testing.T) {
  fmt.Println(math.Sqrt(4))
}

=== RUN   TestSqrt
2
--- PASS: TestSqrt (0.00s)
PASS

Cube Root

func TestCube(t *testing.T) {
   fmt.Println(math.Cbrt(8))
   fmt.Println(math.Cbrt(27))
}

=== RUN   TestCube
2
3
--- PASS: TestCube (0.00s)
PASS

Nth Root

func TestN(t *testing.T) {
  fmt.Println(math.Round(math.Pow(8, 1.0/3)))
  fmt.Println(math.Round(math.Pow(100, 1.0/2)))
}

=== RUN   TestN
2
10
--- PASS: TestN (0.00s)
PASS

Sin

func TestSin(t *testing.T) {
   fmt.Println(math.Sin(0))
   fmt.Println(math.Sin(20))
}

=== RUN   TestSin
0
0.9129452507276277
--- PASS: TestSin (0.00s)
PASS

Cos

func TestCos(t *testing.T) {
   fmt.Println(math.Cos(0))
   fmt.Println(math.Cos(20))
}

=== RUN   TestCos
1
0.40808206181339196
--- PASS: TestCos (0.00s)
PASS

Tan

func TestTan(t *testing.T) {
   fmt.Println(math.Tan(0))
   fmt.Println(math.Tan(20))
}

=== RUN   TestTan
0
2.2371609442247427
--- PASS: TestTan (0.00s)
PASS

TIP

The math package contains far more functions than those listed above, but it is already sufficient for daily use. If you need to delve deeper, you can read the source code yourself.

Complete Example

The program below runs as-is: copy it into a file and execute go run main.go, or paste it into the Go Playground.

package main

import (
	"fmt"
	"math"
)

func main() {
	fmt.Printf("%.4f\n", math.Sqrt2)
	fmt.Println(math.Max(3, 7))
	fmt.Println(math.Pow(2, 10))
	fmt.Println(math.Floor(2.9), math.Ceil(2.1))
	fmt.Println(math.IsNaN(math.NaN()))
}

Expected output:

1.4142
7
1024
2 3
true

Common Pitfalls

• Floating point equality is unreliable. Compare math.Abs(a-b) < 1e-9 instead of a == b.
• NaN is never equal to itself. Use math.IsNaN; use math.IsInf for infinities.
• Arguments are float64. Convert integers before calling Pow, Sqrt and friends.
• Integer limits live here too. Constants such as math.MaxInt (Go 1.17+) are handy for bounds checks.
• Rounding modes differ. Floor/Ceil return floats; convert only after you have decided the rounding direction.

Change Log

• 2026-10-14: Added "Before You Start" notes, a complete runnable example with expected output, common pitfalls, and this change log.