lancet/docs/mathutil_zh-CN.md

Mathutil

mathutil 包实现了一些数学计算的函数.

源码:

https://github.com/duke-git/lancet/blob/v1/mathutil/mathutil.go

用法:

import (
    "github.com/duke-git/lancet/mathutil"
)

目录

• Exponent

• Fibonacci

• Factorial

• Percent

• RoundToFloat

• RoundToString

• TruncRound

Documentation

Exponent

指数计算（x的n次方）

函数签名:

func Exponent(x, n int64) int64

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/mathutil"
)

func main() {
    fmt.Println(mathutil.Exponent(10, 0)) //1
    fmt.Println(mathutil.Exponent(10, 1)) //10
    fmt.Println(mathutil.Exponent(10, 2)) //100
}

Fibonacci

计算斐波那契数列的第n个数

函数签名:

func Fibonacci(first, second, n int) int

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/mathutil"
)

func main() {
    fmt.Println(mathutil.Fibonacci(1, 1, 1)) //1
    fmt.Println(mathutil.Fibonacci(1, 1, 2)) //1
    fmt.Println(mathutil.Fibonacci(1, 1, 3)) //2
    fmt.Println(mathutil.Fibonacci(1, 1, 4)) //3
    fmt.Println(mathutil.Fibonacci(1, 1, 5)) //5
}

Factorial

计算阶乘

函数签名:

func Factorial(x uint) uint

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/mathutil"
)

func main() {
    fmt.Println(mathutil.Factorial(0)) //1
    fmt.Println(mathutil.Factorial(1)) //1
    fmt.Println(mathutil.Factorial(2)) //2
    fmt.Println(mathutil.Factorial(3)) //6
}

Percent

计算百分比，保留n位小数

函数签名:

func Percent(val, total float64, n int) float64

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/mathutil"
)

func main() {
    fmt.Println(mathutil.Percent(1, 2, 2)) //1
    fmt.Println(mathutil.Percent(0.1, 0.3, 2)) //33.33
}

RoundToFloat

四舍五入，保留n位小数

函数签名:

func RoundToFloat(x float64, n int) float64

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/mathutil"
)

func main() {
    fmt.Println(mathutil.RoundToFloat(0, 0)) //0
    fmt.Println(mathutil.RoundToFloat(0, 1)) //0
    fmt.Println(mathutil.RoundToFloat(0.124, 2)) //0.12
    fmt.Println(mathutil.RoundToFloat(0.125, 2)) //0.13
    fmt.Println(mathutil.RoundToFloat(0.125, 3)) //0.125
}

RoundToString

四舍五入，保留n位小数，返回字符串

函数签名:

func RoundToString(x float64, n int) string

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/mathutil"
)

func main() {
    fmt.Println(mathutil.RoundToString(0, 0)) //"0"
    fmt.Println(mathutil.RoundToString(0, 1)) //"0.0:
    fmt.Println(mathutil.RoundToString(0.124, 2)) //"0.12"
    fmt.Println(mathutil.RoundToString(0.125, 2)) //"0.13"
    fmt.Println(mathutil.RoundToString(0.125, 3)) //"0.125"
}

TruncRound

截短n位小数（不进行四舍五入）

函数签名:

func TruncRound(x float64, n int) float64

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/mathutil"
)

func main() {
    fmt.Println(mathutil.TruncRound(0, 0)) //0
    fmt.Println(mathutil.TruncRound(0, 1)) //0
    fmt.Println(mathutil.TruncRound(0.124, 2)) //0.12
    fmt.Println(mathutil.TruncRound(0.125, 2)) //0.12
    fmt.Println(mathutil.TruncRound(0.125, 3)) //0.125
}