📜  C#中的MathF.Log()方法与示例

📅  最后修改于: 2021-05-29 17:14:32             🧑  作者: Mango

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()方法的重载列表中总共有2种方法,如下所示:

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

MathF.Log(Single)方法

此方法用于返回指定数字的自然对数(以e为底)。

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method将返回自然对数或log e (val)
  • 如果参数为零,则结果为NegativeInfinity
  • 如果参数为Negative(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

例子:

// 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)方法

此方法用于以指定的底数返回指定数字的对数。

返回值:返回x的对数,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:

val base Returned Value
val > 0 (0 < Base < 1) or(Base > 1) logbase(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

例子:

// 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