Math.Log 메서드

참조

정의

네임스페이스:: System

어셈블리:: System.Runtime.Extensions.dll

어셈블리:: System.Runtime.dll

어셈블리:: mscorlib.dll

어셈블리:: netstandard.dll

중요

일부 정보는 릴리스되기 전에 상당 부분 수정될 수 있는 시험판 제품과 관련이 있습니다. Microsoft는 여기에 제공된 정보에 대해 어떠한 명시적이거나 묵시적인 보증도 하지 않습니다.

지정된 숫자의 로그를 반환합니다.

오버로드

Log(Double, Double)	지정된 밑을 사용하여 지정된 숫자의 로그를 반환합니다.
Log(Double)	지정된 숫자의 자연(밑 `e`) 로그를 반환합니다.

Log(Double, Double)

Source:: Math.cs

Source:: Math.cs

Source:: Math.cs

지정된 밑을 사용하여 지정된 숫자의 로그를 반환합니다.

public:
 static double Log(double a, double newBase);

public static double Log (double a, double newBase);

static member Log : double * double -> double

Public Shared Function Log (a As Double, newBase As Double) As Double

매개 변수

a: Double

로그가 있는 숫자입니다.

newBase: Double

로그의 밑입니다.

반환

Double

다음 표에 나와 있는 값 중 하나입니다. +Infinity는 PositiveInfinity, -Infinity는 NegativeInfinity,NaN은 NaN을 의미합니다.

`a`	`newBase`	반환 값
`a` > 0	(0 <`newBase`< 1) -또는- (`newBase`> 1)	lognewBase(a)
`a` < 0	(모든 값)	NaN
(모든 값)	`newBase` < 0	NaN
`a` != 1	`newBase` = 0	NaN
`a` != 1	`newBase` = +Infinity	NaN
`a` = NaN	(모든 값)	NaN
(모든 값)	`newBase` = NaN	NaN
(모든 값)	`newBase` = 1	NaN
`a` = 0	0 <`newBase`< 1	+Infinity
`a` = 0	`newBase` > 1	-Infinity
`a` = +Infinity	0 <`newBase`< 1	-Infinity
`a` = +Infinity	`newBase` > 1	+Infinity
`a` = 1	`newBase` = 0	0
`a` = 1	`newBase` = +Infinity	0

예제

다음 예제에서는 를 사용하여 Log 선택한 값에 대한 특정 로그 ID를 평가합니다.

// Example for the Math::Log( double ) and Math::Log( double, double ) methods.
using namespace System;

// Evaluate logarithmic identities that are functions of two arguments.
void UseBaseAndArg( double argB, double argX )
{
   
   // Evaluate log(B)[X] == 1 / log(X)[B].
   Console::WriteLine( "\n                     Math::Log({1}, {0}) == {2:E16}"
   "\n               1.0 / Math::Log({0}, {1}) == {3:E16}", argB, argX, Math::Log( argX, argB ), 1.0 / Math::Log( argB, argX ) );
   
   // Evaluate log(B)[X] == ln[X] / ln[B].
   Console::WriteLine( "         Math::Log({1}) / Math::Log({0}) == {2:E16}", argB, argX, Math::Log( argX ) / Math::Log( argB ) );
   
   // Evaluate log(B)[X] == log(B)[e] * ln[X].
   Console::WriteLine( "Math::Log(Math::E, {0}) * Math::Log({1}) == {2:E16}", argB, argX, Math::Log( Math::E, argB ) * Math::Log( argX ) );
}

void main()
{
   Console::WriteLine( "This example of Math::Log( double ) and "
   "Math::Log( double, double )\n"
   "generates the following output.\n" );
   Console::WriteLine( "Evaluate these identities with "
   "selected values for X and B (base):" );
   Console::WriteLine( "   log(B)[X] == 1 / log(X)[B]" );
   Console::WriteLine( "   log(B)[X] == ln[X] / ln[B]" );
   Console::WriteLine( "   log(B)[X] == log(B)[e] * ln[X]" );
   UseBaseAndArg( 0.1, 1.2 );
   UseBaseAndArg( 1.2, 4.9 );
   UseBaseAndArg( 4.9, 9.9 );
   UseBaseAndArg( 9.9, 0.1 );
}

/*
This example of Math::Log( double ) and Math::Log( double, double )
generates the following output.

Evaluate these identities with selected values for X and B (base):
   log(B)[X] == 1 / log(X)[B]
   log(B)[X] == ln[X] / ln[B]
   log(B)[X] == log(B)[e] * ln[X]

                     Math::Log(1.2, 0.1) == -7.9181246047624818E-002
               1.0 / Math::Log(0.1, 1.2) == -7.9181246047624818E-002
         Math::Log(1.2) / Math::Log(0.1) == -7.9181246047624818E-002
Math::Log(Math::E, 0.1) * Math::Log(1.2) == -7.9181246047624804E-002

                     Math::Log(4.9, 1.2) == 8.7166610085093179E+000
               1.0 / Math::Log(1.2, 4.9) == 8.7166610085093161E+000
         Math::Log(4.9) / Math::Log(1.2) == 8.7166610085093179E+000
Math::Log(Math::E, 1.2) * Math::Log(4.9) == 8.7166610085093179E+000

                     Math::Log(9.9, 4.9) == 1.4425396251981288E+000
               1.0 / Math::Log(4.9, 9.9) == 1.4425396251981288E+000
         Math::Log(9.9) / Math::Log(4.9) == 1.4425396251981288E+000
Math::Log(Math::E, 4.9) * Math::Log(9.9) == 1.4425396251981288E+000

                     Math::Log(0.1, 9.9) == -1.0043839404494075E+000
               1.0 / Math::Log(9.9, 0.1) == -1.0043839404494075E+000
         Math::Log(0.1) / Math::Log(9.9) == -1.0043839404494075E+000
Math::Log(Math::E, 9.9) * Math::Log(0.1) == -1.0043839404494077E+000
*/

// Example for the Math.Log( double ) and Math.Log( double, double ) methods.
using System;

class LogDLogDD
{
    public static void Main()
    {
        Console.WriteLine(
            "This example of Math.Log( double ) and " +
            "Math.Log( double, double )\n" +
            "generates the following output.\n" );
        Console.WriteLine(
            "Evaluate these identities with " +
            "selected values for X and B (base):" );
        Console.WriteLine( "   log(B)[X] == 1 / log(X)[B]" );
        Console.WriteLine( "   log(B)[X] == ln[X] / ln[B]" );
        Console.WriteLine( "   log(B)[X] == log(B)[e] * ln[X]" );

        UseBaseAndArg(0.1, 1.2);
        UseBaseAndArg(1.2, 4.9);
        UseBaseAndArg(4.9, 9.9);
        UseBaseAndArg(9.9, 0.1);
    }

    // Evaluate logarithmic identities that are functions of two arguments.
    static void UseBaseAndArg(double argB, double argX)
    {
        // Evaluate log(B)[X] == 1 / log(X)[B].
        Console.WriteLine(
            "\n                   Math.Log({1}, {0}) == {2:E16}" +
            "\n             1.0 / Math.Log({0}, {1}) == {3:E16}",
            argB, argX, Math.Log(argX, argB),
            1.0 / Math.Log(argB, argX) );

        // Evaluate log(B)[X] == ln[X] / ln[B].
        Console.WriteLine(
            "        Math.Log({1}) / Math.Log({0}) == {2:E16}",
            argB, argX, Math.Log(argX) / Math.Log(argB) );

        // Evaluate log(B)[X] == log(B)[e] * ln[X].
        Console.WriteLine(
            "Math.Log(Math.E, {0}) * Math.Log({1}) == {2:E16}",
            argB, argX, Math.Log(Math.E, argB) * Math.Log(argX) );
    }
}

/*
This example of Math.Log( double ) and Math.Log( double, double )
generates the following output.

Evaluate these identities with selected values for X and B (base):
   log(B)[X] == 1 / log(X)[B]
   log(B)[X] == ln[X] / ln[B]
   log(B)[X] == log(B)[e] * ln[X]

                   Math.Log(1.2, 0.1) == -7.9181246047624818E-002
             1.0 / Math.Log(0.1, 1.2) == -7.9181246047624818E-002
        Math.Log(1.2) / Math.Log(0.1) == -7.9181246047624818E-002
Math.Log(Math.E, 0.1) * Math.Log(1.2) == -7.9181246047624804E-002

                   Math.Log(4.9, 1.2) == 8.7166610085093179E+000
             1.0 / Math.Log(1.2, 4.9) == 8.7166610085093161E+000
        Math.Log(4.9) / Math.Log(1.2) == 8.7166610085093179E+000
Math.Log(Math.E, 1.2) * Math.Log(4.9) == 8.7166610085093179E+000

                   Math.Log(9.9, 4.9) == 1.4425396251981288E+000
             1.0 / Math.Log(4.9, 9.9) == 1.4425396251981288E+000
        Math.Log(9.9) / Math.Log(4.9) == 1.4425396251981288E+000
Math.Log(Math.E, 4.9) * Math.Log(9.9) == 1.4425396251981288E+000

                   Math.Log(0.1, 9.9) == -1.0043839404494075E+000
             1.0 / Math.Log(9.9, 0.1) == -1.0043839404494075E+000
        Math.Log(0.1) / Math.Log(9.9) == -1.0043839404494075E+000
Math.Log(Math.E, 9.9) * Math.Log(0.1) == -1.0043839404494077E+000
*/

// Example for the Math.Log( double ) and Math.Log( double, double ) methods.
open System

// Evaluate logarithmic identities that are functions of two arguments.
let useBaseAndArg argB argX =
    // Evaluate log(B)[X] == 1 / log(X)[B].
    printfn $"""
                   Math.Log({argX}, {argB}) == {Math.Log(argX, argB):E16}
             1.0 / Math.Log({argB}, {argX}) == {1. / Math.Log(argB, argX):E16}"""

    // Evaluate log(B)[X] == ln[X] / ln[B].
    printfn $"        Math.Log({argX}) / Math.Log({argB}) == {Math.Log argX / Math.Log argB:E16}"

    // Evaluate log(B)[X] == log(B)[e] * ln[X].
    printfn $"Math.Log(Math.E, {argB}) * Math.Log({argX}) == {Math.Log(Math.E, argB) * Math.Log argX:E16}"


printfn
    """This example of Math.Log( double ) and Math.Log( double, double )
generates the following output.

printfn "Evaluate these identities with selected values for X and B (base):"""
printfn "   log(B)[X] == 1 / log(X)[B]"
printfn "   log(B)[X] == ln[X] / ln[B]" 
printfn "   log(B)[X] == log(B)[e] * ln[X]" 

useBaseAndArg 0.1 1.2
useBaseAndArg 1.2 4.9
useBaseAndArg 4.9 9.9
useBaseAndArg 9.9 0.1


// This example of Math.Log( double ) and Math.Log( double, double )
// generates the following output.
//
// Evaluate these identities with selected values for X and B (base):
//    log(B)[X] == 1 / log(X)[B]
//    log(B)[X] == ln[X] / ln[B]
//    log(B)[X] == log(B)[e] * ln[X]
//
//                    Math.Log(1.2, 0.1) == -7.9181246047624818E-002
//              1.0 / Math.Log(0.1, 1.2) == -7.9181246047624818E-002
//         Math.Log(1.2) / Math.Log(0.1) == -7.9181246047624818E-002
// Math.Log(Math.E, 0.1) * Math.Log(1.2) == -7.9181246047624804E-002
//
//                    Math.Log(4.9, 1.2) == 8.7166610085093179E+000
//              1.0 / Math.Log(1.2, 4.9) == 8.7166610085093161E+000
//         Math.Log(4.9) / Math.Log(1.2) == 8.7166610085093179E+000
// Math.Log(Math.E, 1.2) * Math.Log(4.9) == 8.7166610085093179E+000
//
//                    Math.Log(9.9, 4.9) == 1.4425396251981288E+000
//              1.0 / Math.Log(4.9, 9.9) == 1.4425396251981288E+000
//         Math.Log(9.9) / Math.Log(4.9) == 1.4425396251981288E+000
// Math.Log(Math.E, 4.9) * Math.Log(9.9) == 1.4425396251981288E+000
//
//                    Math.Log(0.1, 9.9) == -1.0043839404494075E+000
//              1.0 / Math.Log(9.9, 0.1) == -1.0043839404494075E+000
//         Math.Log(0.1) / Math.Log(9.9) == -1.0043839404494075E+000
// Math.Log(Math.E, 9.9) * Math.Log(0.1) == -1.0043839404494077E+000

' Example for the Math.Log( Double ) and Math.Log( Double, Double ) methods.
Module LogDLogDD
   
    Sub Main()
        Console.WriteLine( _
            "This example of Math.Log( Double ) and " + _
            "Math.Log( Double, Double )" & vbCrLf & _
            "generates the following output." & vbCrLf)
        Console.WriteLine( _
            "Evaluate these identities with selected " & _
            "values for X and B (base):")
        Console.WriteLine("   log(B)[X] = 1 / log(X)[B]")
        Console.WriteLine("   log(B)[X] = ln[X] / ln[B]")
        Console.WriteLine("   log(B)[X] = log(B)[e] * ln[X]")
          
        UseBaseAndArg(0.1, 1.2)
        UseBaseAndArg(1.2, 4.9)
        UseBaseAndArg(4.9, 9.9)
        UseBaseAndArg(9.9, 0.1)
    End Sub
       
    ' Evaluate logarithmic identities that are functions of two arguments.
    Sub UseBaseAndArg(argB As Double, argX As Double)

        ' Evaluate log(B)[X] = 1 / log(X)[B].
        Console.WriteLine( _
            vbCrLf & "                   Math.Log({1}, {0}) = {2:E16}" + _
            vbCrLf & "             1.0 / Math.Log({0}, {1}) = {3:E16}", _
            argB, argX, Math.Log(argX, argB), _
            1.0 / Math.Log(argB, argX))
          
        ' Evaluate log(B)[X] = ln[X] / ln[B].
        Console.WriteLine( _
            "        Math.Log({1}) / Math.Log({0}) = {2:E16}", _
            argB, argX, Math.Log(argX) / Math.Log(argB))
          
        ' Evaluate log(B)[X] = log(B)[e] * ln[X].
        Console.WriteLine( _
            "Math.Log(Math.E, {0}) * Math.Log({1}) = {2:E16}", _
            argB, argX, Math.Log(Math.E, argB) * Math.Log(argX))

    End Sub
End Module 'LogDLogDD

' This example of Math.Log( Double ) and Math.Log( Double, Double )
' generates the following output.
' 
' Evaluate these identities with selected values for X and B (base):
'    log(B)[X] = 1 / log(X)[B]
'    log(B)[X] = ln[X] / ln[B]
'    log(B)[X] = log(B)[e] * ln[X]
' 
'                    Math.Log(1.2, 0.1) = -7.9181246047624818E-002
'              1.0 / Math.Log(0.1, 1.2) = -7.9181246047624818E-002
'         Math.Log(1.2) / Math.Log(0.1) = -7.9181246047624818E-002
' Math.Log(Math.E, 0.1) * Math.Log(1.2) = -7.9181246047624804E-002
' 
'                    Math.Log(4.9, 1.2) = 8.7166610085093179E+000
'              1.0 / Math.Log(1.2, 4.9) = 8.7166610085093161E+000
'         Math.Log(4.9) / Math.Log(1.2) = 8.7166610085093179E+000
' Math.Log(Math.E, 1.2) * Math.Log(4.9) = 8.7166610085093179E+000
' 
'                    Math.Log(9.9, 4.9) = 1.4425396251981288E+000
'              1.0 / Math.Log(4.9, 9.9) = 1.4425396251981288E+000
'         Math.Log(9.9) / Math.Log(4.9) = 1.4425396251981288E+000
' Math.Log(Math.E, 4.9) * Math.Log(9.9) = 1.4425396251981288E+000
' 
'                    Math.Log(0.1, 9.9) = -1.0043839404494075E+000
'              1.0 / Math.Log(9.9, 0.1) = -1.0043839404494075E+000
'         Math.Log(0.1) / Math.Log(9.9) = -1.0043839404494075E+000
' Math.Log(Math.E, 9.9) * Math.Log(0.1) = -1.0043839404494077E+000

설명

이 메서드는 기본 C 런타임을 호출하며 정확한 결과 또는 유효한 입력 범위는 서로 다른 운영 체제 또는 아키텍처 간에 다를 수 있습니다.

적용 대상

Log(Double)

Source:: Math.cs

Source:: Math.cs

Source:: Math.cs

지정된 숫자의 자연(밑 e) 로그를 반환합니다.

public:
 static double Log(double d);

public static double Log (double d);

static member Log : double -> double

Public Shared Function Log (d As Double) As Double

매개 변수

d: Double

로그가 있는 숫자입니다.

반환

Double

다음 표에 나와 있는 값 중 하나입니다.

`d` 매개 변수	반환 값
양수	`d`의 자연 로그인 ln `d` 또는 log e `d`
0	NegativeInfinity
음수	NaN
NaN과 같습니다.	NaN
PositiveInfinity과 같습니다.	PositiveInfinity

예제

다음 예제에서는 메서드를 Log 보여 줍니다.

using System;
public class Example
{
   public static void Main()
   {
      Console.WriteLine("  Evaluate this identity with selected values for X:");
      Console.WriteLine("                              ln(x) = 1 / log[X](B)");
      Console.WriteLine();

      double[] XArgs = { 1.2, 4.9, 9.9, 0.1 };

      foreach (double argX in XArgs)
      {
         // Find natural log of argX.
         Console.WriteLine("                      Math.Log({0}) = {1:E16}",
                           argX, Math.Log(argX));

         // Evaluate 1 / log[X](e).
         Console.WriteLine("             1.0 / Math.Log(e, {0}) = {1:E16}",
                           argX, 1.0 / Math.Log(Math.E, argX));
         Console.WriteLine();
      }
   }
}
// This example displays the following output:
//         Evaluate this identity with selected values for X:
//                                     ln(x) = 1 / log[X](B)
//
//                             Math.Log(1.2) = 1.8232155679395459E-001
//                    1.0 / Math.Log(e, 1.2) = 1.8232155679395459E-001
//
//                             Math.Log(4.9) = 1.5892352051165810E+000
//                    1.0 / Math.Log(e, 4.9) = 1.5892352051165810E+000
//
//                             Math.Log(9.9) = 2.2925347571405443E+000
//                    1.0 / Math.Log(e, 9.9) = 2.2925347571405443E+000
//
//                             Math.Log(0.1) = -2.3025850929940455E+000
//                    1.0 / Math.Log(e, 0.1) = -2.3025850929940455E+000

open System

printfn "  Evaluate this identity with selected values for X:"
printfn "                              ln(x) = 1 / log[X](B)\n"

let XArgs = [| 1.2; 4.9; 9.9; 0.1 |]

for argX in XArgs do
    // Find natural log of argX.
    // The F# log function may be used instead
    printfn $"                      Math.Log({argX}) = {Math.Log argX:E16}"

    // Evaluate 1 / log[X](e).
    printfn $"             1.0 / Math.Log(e, {argX}) = {1. / Math.Log(Math.E, argX):E16}\n"

// This example displays the following output:
//         Evaluate this identity with selected values for X:
//                                     ln(x) = 1 / log[X](B)
//
//                             Math.Log(1.2) = 1.8232155679395459E-001
//                    1.0 / Math.Log(e, 1.2) = 1.8232155679395459E-001
//
//                             Math.Log(4.9) = 1.5892352051165810E+000
//                    1.0 / Math.Log(e, 4.9) = 1.5892352051165810E+000
//
//                             Math.Log(9.9) = 2.2925347571405443E+000
//                    1.0 / Math.Log(e, 9.9) = 2.2925347571405443E+000
//
//                             Math.Log(0.1) = -2.3025850929940455E+000
//                    1.0 / Math.Log(e, 0.1) = -2.3025850929940455E+000

Module Example
   Sub Main()
      Console.WriteLine( _
         "  Evaluate this identity with selected values for X:")
      Console.WriteLine("                              ln(x) = 1 / log[X](B)")
      Console.WriteLine()
          
      Dim XArgs() As Double = { 1.2, 4.9, 9.9, 0.1 }
   
      For Each argX As Double In XArgs
         ' Find natural log of argX.
         Console.WriteLine("                      Math.Log({0}) = {1:E16}", _
                           argX, Math.Log(argX))

         ' Evaluate 1 / log[X](e).
         Console.WriteLine("             1.0 / Math.Log(e, {0}) = {1:E16}", _
                           argX, 1.0 / Math.Log(Math.E, argX))
         Console.WriteLine()
      Next
   End Sub 
End Module
' This example displays the following output:
'         Evaluate this identity with selected values for X:
'                                     ln(x) = 1 / log[X](B)
'       
'                             Math.Log(1.2) = 1.8232155679395459E-001
'                    1.0 / Math.Log(e, 1.2) = 1.8232155679395459E-001
'       
'                             Math.Log(4.9) = 1.5892352051165810E+000
'                    1.0 / Math.Log(e, 4.9) = 1.5892352051165810E+000
'       
'                             Math.Log(9.9) = 2.2925347571405443E+000
'                    1.0 / Math.Log(e, 9.9) = 2.2925347571405443E+000
'       
'                             Math.Log(0.1) = -2.3025850929940455E+000
'                    1.0 / Math.Log(e, 0.1) = -2.3025850929940455E+000

설명

매개 변수 d 는 기본 10 숫자로 지정됩니다.

이 메서드는 기본 C 런타임을 호출하며 정확한 결과 또는 유효한 입력 범위는 서로 다른 운영 체제 또는 아키텍처 간에 다를 수 있습니다.

추가 정보

적용 대상

다음을 통해 공유

Math.Log 메서드

정의

오버로드

Log(Double, Double)

매개 변수

반환

예제

설명

적용 대상

Log(Double)

매개 변수

반환

예제

설명

추가 정보

적용 대상

추가 리소스