github.com/Anderson-Lu/gobox@v0.0.0-20191127065433-3e6c4c2da420/number/number_helper.go (about)

     1  package number
     2  
     3  import (
     4  	"math"
     5  	"math/rand"
     6  	"strconv"
     7  	"strings"
     8  )
     9  
    10  /*
    11  * Return random int value between 0 and max-1
    12   */
    13  func RandomInt(max int) int {
    14  	return rand.Intn(max)
    15  }
    16  
    17  /*
    18  * Return the min value between a1 and a2
    19   */
    20  func Min(a1, a2 float64) float64 {
    21  	if a1 < a2 {
    22  		return a1
    23  	}
    24  	return a2
    25  }
    26  
    27  /*
    28  * Return the min value between a1 to aN
    29   */
    30  func MinN(aN ...int) int {
    31  	ret := math.MaxInt16
    32  	for _, v := range aN {
    33  		if v < ret {
    34  			ret = v
    35  		}
    36  	}
    37  	return ret
    38  }
    39  
    40  /*
    41  * Return the min value between a1 to aN
    42   */
    43  func MinFloat64N(aN ...float64) float64 {
    44  	ret := math.MaxFloat64
    45  	for _, v := range aN {
    46  		if v < ret {
    47  			ret = v
    48  		}
    49  	}
    50  	return ret
    51  }
    52  
    53  //向上或者向下按照有效位数取整
    54  //n为有效位数
    55  //raw为原始数字
    56  //isUp是否向上取整,否则为向下取整
    57  func FloorOrCeil(n int, raw float64, isUp bool) float64 {
    58  
    59  	if raw >= math.Pow(10.0, float64(n)) {
    60  		return raw
    61  	}
    62  
    63  	t := strconv.FormatFloat(raw, 'G', n, 64)
    64  	ret, _ := strconv.ParseFloat(t, 64)
    65  	t1 := strconv.FormatFloat(raw, 'G', n+1, 64)
    66  	ret1, _ := strconv.ParseFloat(t1, 64)
    67  	pointIndex := strings.Index(t1, ".")
    68  
    69  	lastCh, _ := strconv.ParseInt(t1[len(t1)-1:], 10, 64)
    70  	isNotZero := (ret1-ret != 0)
    71  
    72  	if !isNotZero {
    73  		return ret
    74  	}
    75  
    76  	points := len(t1) - pointIndex - 1
    77  
    78  	//整数位数大于小数位数
    79  	if pointIndex > points && pointIndex == n && points != 1 {
    80  
    81  		if isUp && lastCh < 5 {
    82  			ret += 1.0
    83  		}
    84  
    85  		if isNotZero && lastCh >= 5 && !isUp && points != 0 {
    86  			ret -= 1.0
    87  		}
    88  	} else if pointIndex > points && pointIndex == n && points == 1 {
    89  		if lastCh <= 5 && isUp {
    90  			ret += 1.0
    91  		}
    92  		if lastCh > 5 && !isUp {
    93  			ret -= 1.0
    94  		}
    95  	} else {
    96  
    97  		fator := math.Pow(10, float64(-points+1))
    98  
    99  		if isUp {
   100  
   101  			if isNotZero && lastCh < 5 {
   102  				ret += fator
   103  			} else if isNotZero && lastCh <= 5 && points == 2 {
   104  				ret += fator
   105  			}
   106  		}
   107  
   108  		if isNotZero && lastCh >= 5 && !isUp && points != 2 {
   109  			ret -= fator
   110  		}
   111  	}
   112  
   113  	tmp := strconv.FormatFloat(ret, 'G', n, 64) //3.3343
   114  	ret, _ = strconv.ParseFloat(tmp, 64)
   115  	return ret
   116  }
   117  
   118  //判断有多少位精度
   119  func CalcDigist(n float64) int {
   120  	switch n {
   121  	case 0.1:
   122  		return 1
   123  	case 0.01:
   124  		return 2
   125  	case 0.001:
   126  		return 3
   127  	case 0.0001:
   128  		return 4
   129  	case 0.00001:
   130  		return 5
   131  	case 0.000001:
   132  		return 6
   133  	case 0.0000001:
   134  		return 7
   135  	case 0.00000001:
   136  		return 8
   137  	default:
   138  		return -1
   139  	}
   140  }
   141  
   142  //按照指定精度位数向上或者向下取整
   143  func Round(f float64, n int) float64 {
   144  	var i int = 1
   145  	var count int = 0
   146  	for {
   147  		if int(f/float64(i)) > 0 {
   148  			i *= 10
   149  			count++
   150  			continue
   151  		}
   152  		break
   153  	}
   154  	return FloorOrCeil(count+n, f, false)
   155  }
   156  
   157  func f(x, a float64) float64 {
   158  	return math.Exp(x) - a
   159  }
   160  
   161  func Ln(n float64) float64 {
   162  	var lo, hi, m float64
   163  	if n <= 0 {
   164  		return -1
   165  	}
   166  	if n == 1 {
   167  		return 0
   168  	}
   169  	EPS := 0.00001
   170  	lo = 0
   171  	hi = n
   172  	for math.Abs(lo-hi) >= EPS {
   173  		m = float64((lo + hi) / 2.0)
   174  		if f(m, n) < 0 {
   175  			lo = m
   176  		} else {
   177  			hi = m
   178  		}
   179  	}
   180  	return float64((lo + hi) / 2.0)
   181  }