Golang Math Package Examples [Tutorial]

The built-in math package in Go is made up entirely of math functions and constants that can be used to perform various tasks. Most of the functions work with float64 type here. We need to import the package first.

import "math"

Package math provides basic constants and mathematical functions.

GO Math Constants

Math package provides some 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
)

It also defines integer limit values:

const (
	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
)

Using math constants to calculate the area and circumference of a circle

Example of using constants in Go to read the radius input and calculate the area and circumference of a circle:

package main

import (
	"fmt"
	"math"
)

func main() {
	var rad float64
	var area float64
	var ci float64

	//user input the radius of the Cirle
	fmt.Print("Enter radius of Circle : ")
	fmt.Scanln(&rad)
	area = math.Pi * rad * rad

	fmt.Println("Area of Circle is : ", area)
	ci = 2 * math.Pi * rad
	fmt.Println("Circumference of Circle is : ", ci)
}

Output:

Enter radius of Circle : 1.2
Area of Circle is :  4.523893421169302
Circumference of Circle is :  7.5398223686155035

Math Functions

For special cases for each function, visit the Go Math package documentation.

Using math functions to solve quadratic problem

Here's a quick example on how to do quadratic calculations (ax²+bx+c) in Golang. This program accepts three floating point values from the stdin and uses the quadratic formula to calculate the roots.

package main

import (
	"fmt"
	"math"
)

func main() {

	var a, b, c, x1, x2, discriminant float64

	fmt.Print("Enter a, b, c = ")
	fmt.Scanln(&a, &b, &c)

	//use Pow function
	discriminant = math.Pow(b, 2) - (4 * a * c)

	if discriminant > 0 {
		// use Sqrt function
		x1 = (-b + math.Sqrt(discriminant)/(2*a))
		x2 = (-b - math.Sqrt(discriminant)/(2*a))
		fmt.Println("x1 = ", x1, " and x2 = ", x2)
	} else if discriminant == 0 {
		x1 = -b / (2 * a)
		x2 = -b / (2 * a)
		fmt.Println("x1 = ", x1, " and x2 = ", x2)
	} else if discriminant < 0 {
		fmt.Println("Can not solve the problem")
	}
}

Output:

Enter a, b, c = 1 2 1
x1 =  -1  and x2 =  -1

Enter a, b, c = 1 2 3
Can not solve the problem

Math sub-packages

The math package includes useful sub-packages such as the rand package, which includes methods for generating random numbers. Crypto/rand is recommended for generating cryptographically secure random numbers. The big package handles arbitrary large integers. The bit manipulation segment is handled by the bits package. The cmplx package should be used when working with complex numbers.

package main

import (
	"fmt"
	"math/cmplx"
)

func main() {
	comp1 := complex(1, -2)        // constructor init
	comp2 := 2 + 3i                // complex initializer syntax a + ib
	comp3 := comp1 + comp2         // addition just like other variables
	compPow := cmplx.Pow(comp3, 2) // pow with complex number
	compSqrt := cmplx.Sqrt(comp3)  // square with complex number
	fmt.Println("Add: ", comp3)    
	re := real(comp3)              // get real part
	im := imag(comp3)              // get imaginary part
	fmt.Println(re, im)
	fmt.Println(compPow)
	fmt.Println(compSqrt)
}

Add:  (3+1i)
3 1
(8.000000000000002+6.000000000000001i)
(1.755317301824428+0.28484878459314106i)