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 ```go // 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 // 2127 * (224 - 1) / 223 SmallestNonzeroFloat32 = 1.401298464324817070923729583289916131280e-45 // 1 / 2(127 - 1 + 23)

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

  2. - 列举出常用的数学函数
  3. ```go
  4.     var i, j float64 = 12.3, 9.6
  5.     //向下取整,
  6.     fmt.Println(math.Floor(i)) //输出:12
  7.     //向上取整
  8.     fmt.Println(math.Ceil(i)) //输出:13
  9.     //绝对值
  10.     fmt.Println(math.Abs(i)) //输出:12.3
  11.     //返回值分别整数位和小数位,小数位可能出现误差
  12.     num, decimal := math.Modf(i)
  13.     fmt.Println(num, decimal)
  14.     //返回两个变量中大的值
  15.     fmt.Println(math.Max(i, j)) //输出:12.3
  16.     //返回两个变量中小的值
  17.     fmt.Println(math.Min(i, j)) //输出:9.6
  18.     //x的y次方
  19.     fmt.Println(math.Pow(3, 2)) //输出:输出9
  20.     //四舍五入
  21.     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
    1.   rand.Seed(time.Now().UnixNano())
    2.   fmt.Println(rand.Int63n(10))