C# MathF.Log()用法及代码示例

在C#中，MathF.Log()是MathF类方法。用于返回指定数字的对数。可以通过更改传递的参数数量来重载此方法。 MathF.Log()方法的重载列表中共有2种方法，如下所示：

MathF.Log(Single)方法
MathF.Log(Single, Single)方法

MathF.Log(Single) Method

此方法用于返回指定数字的自然对数(以e为底)。

用法： public static float Log (float x);

Here, x is the specified number whose natural (base e) logarithm to be calculated and its type is System.Single.

返回值：返回x的自然对数，其类型为System.Single。

注意：参数x始终指定为以10为底的数字。返回值取决于传递的参数。以下是一些情况：

如果参数为正，则方法将返回自然对数或loge(val)。
如果参数为零，则结果为NegativeInfinity。
如果参数为负(小于零)或等于NaN，则结果为NaN。
如果参数为PositiveInfinity，则结果为PositiveInfinity。
如果参数为NegativeInfinity，则结果为NaN。

例：

// C# program to demonstrate working 
// of MathF.Log(Single) method 
using System; 
  
class Geeks { 
  
    // Main Method 
    public static void Main(String[] args) 
    { 
  
        // Single values whose logarithm 
        // to be calculated 
        float a = 9.78f; 
        float b = 0f; 
        float c = -4.56f; 
        float nan = Single.NaN; 
        float positiveInfinity = Single.PositiveInfinity; 
        float negativeInfinity = Single.NegativeInfinity; 
  
        // Input is positive number so output 
        // will be logarithm of number 
        Console.WriteLine(MathF.Log(a)); 
  
        // positive zero as argument, so output 
        // will be -Infinity 
        Console.WriteLine(MathF.Log(b)); 
  
        // Input is negative number so output 
        // will be NaN 
        Console.WriteLine(MathF.Log(c)); 
  
        // Input is NaN so output 
        // will be NaN 
        Console.WriteLine(MathF.Log(nan)); 
  
        // Input is PositiveInfinity so output 
        // will be Infinity 
        Console.WriteLine(MathF.Log(positiveInfinity)); 
  
        // Input is NegativeInfinity so output 
        // will be NaN 
        Console.WriteLine(MathF.Log(negativeInfinity)); 
    } 
}

输出：

2.280339
-Infinity
NaN
NaN
Infinity
NaN

Math.Log(Single, Single) Method

此方法用于以指定的底数返回指定数字的对数。

用法： public static float Log (float x, float y);

参数:
x:它是要计算其对数的指定数字，其类型为System.Single。 y：是类型System.Single的对数的底。

返回值：它返回x的对数，其类型为System.Single。

注意：返回值始终取决于传递的参数。下表描述了不同的情况：

值	基础	返回值
val > 0	(0 < Base < 1) or(Base > 1)	log_base(val)
val < 0	any value	NaN
any value	base < 0	NaN
val != 1	base = 0	NaN
val != 1	base = +ve Infinity	NaN
val = NaN	any value	NaN
any value	base = NaN	NaN
any value	base = 1	NaN
val = 0	(0 < Base < 1)	+ve Infinity
val = 0	base > 1	-ve Infinity
val = +ve Infinity	(0 < Base < 1)	-ve Infinity
val = +ve Infinity	base > 1	+ve Infinity
val = 1	base = 0	0
val = 1	base = +ve Infinity	0

例：

// C# program to demonstrate working 
// of MathF.Log(Single, Single) method 
using System; 
  
class Geeks { 
  
    // Main Method 
    public static void Main(String[] args) 
    { 
  
        // Here val = 4.4f and base is 0.4f then 
        // output will be logarithm of given value 
        Console.WriteLine(MathF.Log(4.4f, 0.4f)); 
  
        // Here val is 0.5f and base > 1f then output 
        // will be -0.5f 
        Console.WriteLine(MathF.Log(0.5f, 4f)); 
  
        // Here val is 0.9f and base = 1f then output 
        // will be NaN 
        Console.WriteLine(MathF.Log(0.9f, 1f)); 
  
        // Here val is 0.4f and base is NaN then output 
        // will be NaN 
        Console.WriteLine(MathF.Log(0.4f, Single.NaN)); 
    } 
}

输出：

-1.616959
-0.5
NaN
NaN

相关用法

注：本文由纯净天空筛选整理自Kirti_Mangal大神的英文原创作品 MathF.Log() Method in C# with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。