Math.Log10(Double) メソッド

定義

名前空間:

System

アセンブリ:

System.Runtime.dll

ソース:

Math.cs

指定した数の底 10 の対数を返します。

public:
 static double Log10(double d);

public static double Log10 (double d);

static member Log10 : double -> double

Public Shared Function Log10 (d As Double) As Double

パラメーター

d

Double

対数を検索する対象の数値。

戻り値

Double

次の表に示した値のいずれか

d パラメーター	戻り値
正	d の底 10 の log。つまり、log 10d。
ゼロ	NegativeInfinity
負	NaN
NaN と等価です。	NaN
PositiveInfinity と等価です。	PositiveInfinity

例

次の例では、 メソッドを Log10 使用して、選択した値の底 10 の対数を返します。

using System;

public class Example
{
   public static void Main()
   {
      double[] numbers = {-1, 0, .105, .5, .798, 1, 4, 6.9, 10, 50,
                          100, 500, 1000, Double.MaxValue};

      foreach (double number in numbers)
         Console.WriteLine("The base 10 log of {0} is {1}.",
                           number, Math.Log10(number));
   }
}
// The example dislays the following output:
//       The base 10 log of -1 is NaN.
//       The base 10 log of 0 is -Infinity.
//       The base 10 log of 0.105 is -0.978810700930062.
//       The base 10 log of 0.5 is -0.301029995663981.
//       The base 10 log of 0.798 is -0.0979971086492706.
//       The base 10 log of 1 is 0.
//       The base 10 log of 4 is 0.602059991327962.
//       The base 10 log of 6.9 is 0.838849090737255.
//       The base 10 log of 10 is 1.
//       The base 10 log of 50 is 1.69897000433602.
//       The base 10 log of 100 is 2.
//       The base 10 log of 500 is 2.69897000433602.
//       The base 10 log of 1000 is 3.
//       The base 10 log of 1.79769313486232E+308 is 308.254715559917.

open System

let numbers =
    [ -1.; 0; 0.105; 0.5; 0.798; 1; 4; 6.9; 10
      50; 100; 500; 1000; Double.MaxValue ]

for number in numbers do
    // the F# log10 function may be used instead
    printfn $"The base 10 log of {number} is {Math.Log10 number}."
// The example dislays the following output:
//       The base 10 log of -1 is NaN.
//       The base 10 log of 0 is -Infinity.
//       The base 10 log of 0.105 is -0.978810700930062.
//       The base 10 log of 0.5 is -0.301029995663981.
//       The base 10 log of 0.798 is -0.0979971086492706.
//       The base 10 log of 1 is 0.
//       The base 10 log of 4 is 0.602059991327962.
//       The base 10 log of 6.9 is 0.838849090737255.
//       The base 10 log of 10 is 1.
//       The base 10 log of 50 is 1.69897000433602.
//       The base 10 log of 100 is 2.
//       The base 10 log of 500 is 2.69897000433602.
//       The base 10 log of 1000 is 3.
//       The base 10 log of 1.79769313486232E+308 is 308.254715559917.

Module Example
   Public Sub Main()
      Dim numbers() As Double = {-1, 0, .105, .5, .798, 1, 4, 6.9, 10, 50, _
                                 100, 500, 1000, Double.MaxValue}
      
      For Each number As Double In numbers
         Console.WriteLine("The base 10 log of {0} is {1}.", _
                           number, Math.Log10(number))
      Next
   End Sub
End Module
' The example displays the following output:
'       The base 10 log of -1 is NaN.
'       The base 10 log of 0 is -Infinity.
'       The base 10 log of 0.105 is -0.978810700930062.
'       The base 10 log of 0.5 is -0.301029995663981.
'       The base 10 log of 0.798 is -0.0979971086492706.
'       The base 10 log of 1 is 0.
'       The base 10 log of 4 is 0.602059991327962.
'       The base 10 log of 6.9 is 0.838849090737255.
'       The base 10 log of 10 is 1.
'       The base 10 log of 50 is 1.69897000433602.
'       The base 10 log of 100 is 2.
'       The base 10 log of 500 is 2.69897000433602.
'       The base 10 log of 1000 is 3.
'       The base 10 log of 1.79769313486232E+308 is 308.254715559917.

注釈

パラメーター d は、基数 10 として指定されます。

このメソッドは基になる C ランタイムを呼び出します。正確な結果または有効な入力範囲は、オペレーティング システムやアーキテクチャによって異なる場合があります。