一. 常用数学函数

  • math包提供了基本数学常数和数学函数
  • math包提供的数学常数
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    // Mathematical constants.
    const (
    	E   = 2.71828182845904523536028747135266249775724709369995957496696763 
    	Pi  = 3.14159265358979323846264338327950288419716939937510582097494459 
    	Phi = 1.61803398874989484820458683436563811772030917980576286213544862 
    	Sqrt2   = 1.41421356237309504880168872420969807856967187537694807317667974
    	SqrtE   = 1.64872127070012814684865078781416357165377610071014801157507931 
    	SqrtPi  = 1.77245385090551602729816748334114518279754945612238712821380779 
    	SqrtPhi = 1.27201964951406896425242246173749149171560804184009624861664038 
    	Ln2    = 0.693147180559945309417232121458176568075500134360255254120680009 
    	Log2E  = 1 / Ln2
    	Ln10   = 2.30258509299404568401799145468436420760110148862877297603332790 
    	Log10E = 1 / Ln10
    )

    // Floating-point limit values.
    // Max is the largest finite value representable by the type.
    // SmallestNonzero is the smallest positive, non-zero value representable by the type.
    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)
    )

    // Integer limit values.
    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
    )
  • 列举出常用的数学函数
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    var i, j float64 = 12.3, 9.6
    //向下取整,
    fmt.Println(math.Floor(i)) //输出:12
    //向上取整
    fmt.Println(math.Ceil(i)) //输出:13
    //绝对值
    fmt.Println(math.Abs(i)) //输出:12.3
    //返回值分别整数位和小数位,小数位可能出现误差
    num, decimal := math.Modf(i)
    fmt.Println(num, decimal)
    //返回两个变量中大的值
    fmt.Println(math.Max(i, j)) //输出:12.3
    //返回两个变量中小的值
    fmt.Println(math.Min(i, j)) //输出:9.6
    //x的y次方
    fmt.Println(math.Pow(3, 2)) //输出:输出9
    //四舍五入
    fmt.Println(math.Round(i)) //输出:12

二.随机数

  • math/rand实现了伪随机数生成器
  • 在Go语言中随机数需要设置种子,如果不设置种子随机数的结果每次运行都相同。
  • 默认种子是1,且相同种子产生的随机数是相同的.
  • 可以使用当前时间的纳秒差计算随机数,在一定程度上保证了种子的唯一性
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    rand.Seed(time.Now().UnixNano())
    fmt.Println(rand.Int63n(10))