豆子笔记

数学包提供基本常量和数学函数，此程序包不保证跨体系结构的位数相同。

数学常数

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
)

浮点限制值

const (
        MaxFloat32             = 3.40282346638528859811704183484516925440e+38  // 2**127 * (2**24 - 1) / 2**23
        SmallestNonzeroFloat32 = 1.401298464324817070923729583289916131280e-45 // 1 / 2**(127 - 1 + 23)

        MaxFloat64             = 1.797693134862315708145274237317043567981e+308 // 2**1023 * (2**53 - 1) / 2**52
        SmallestNonzeroFloat64 = 4.940656458412465441765687928682213723651e-324 // 1 / 2**(1023 - 1 + 52)
)

整数限制值

const (
        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
        MaxUint8  = 1<<8 - 1
        MaxUint16 = 1<<16 - 1
        MaxUint32 = 1<<32 - 1
        MaxUint64 = 1<<64 - 1
)

例子：

package main

import (
	"fmt"
	"math"
)

func main() {
	// 地板，取低值
	c := math.Floor(1.51)
	fmt.Printf("%.1f\n", c)
	// 天花板，取高值
	c = math.Ceil(1.49)
	fmt.Printf("%.1f\n", c)
	// 求平方根
	const (
		a = 3
		b = 4
	)
	c = math.Sqrt(a*a + b*b)
	fmt.Printf("%.1f", c)
    // 其它参考官方math包
}