Math.Log Método

Referencia

Definición

Espacio de nombres:: System

Ensamblado:: System.Runtime.Extensions.dll

Ensamblado:: System.Runtime.dll

Ensamblado:: mscorlib.dll

Ensamblado:: netstandard.dll

Importante

Parte de la información hace referencia a la versión preliminar del producto, que puede haberse modificado sustancialmente antes de lanzar la versión definitiva. Microsoft no otorga ninguna garantía, explícita o implícita, con respecto a la información proporcionada aquí.

Devuelve el logaritmo de un número especificado.

Sobrecargas

Log(Double, Double)	Devuelve el logaritmo de un número especificado en una base determinada.
Log(Double)	Devuelve el logaritmo natural (en base `e`) de un número especificado.

Log(Double, Double)

Source:: Math.cs

Source:: Math.cs

Source:: Math.cs

Devuelve el logaritmo de un número especificado en una base determinada.

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

Parámetros

a: Double

Número cuyo logaritmo se va a calcular.

newBase: Double

Base del logaritmo.

Devoluciones

Double

Uno de los valores de la tabla siguiente. (+Infinito denota PositiveInfinity, -Infinito denota NegativeInfinity y NaN denota NaN)

`a`	`newBase`	Valor devuelto
`a` > 0	(0 <`newBase`< 1) -o- (`newBase`> 1)	lognewBase(a)
`a` < 0	(cualquier valor)	NaN
(cualquier valor)	`newBase` < 0	NaN
`a` != 1	`newBase` = 0	NaN
`a` != 1	`newBase` = +Infinito	NaN
`a` = NaN	(cualquier valor)	NaN
(cualquier valor)	`newBase` = NaN	NaN
(cualquier valor)	`newBase` = 1	NaN
`a` = 0	0 <`newBase`< 1	+Infinito
`a` = 0	`newBase` > 1	-Infinity
`a` = +Infinito	0 <`newBase`< 1	-Infinity
`a` = +Infinito	`newBase` > 1	+Infinito
`a` = 1	`newBase` = 0	0
`a` = 1	`newBase` = +Infinito	0

Ejemplos

En el ejemplo siguiente se usa Log para evaluar determinadas identidades logarítmicas para los valores seleccionados.

// 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

Comentarios

Este método llama al entorno de ejecución de C subyacente y el resultado exacto o el intervalo de entrada válido pueden diferir entre diferentes sistemas operativos o arquitecturas.

Se aplica a

Log(Double)

Source:: Math.cs

Source:: Math.cs

Source:: Math.cs

Devuelve el logaritmo natural (en base e) de un número especificado.

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

Parámetros

d: Double

Número cuyo logaritmo se va a calcular.

Devoluciones

Double

Uno de los valores de la tabla siguiente.

Parámetro `d`	Valor devuelto
Positivo	El algoritmo natural de `d`; es decir, ln `d` o log e `d`
Cero	NegativeInfinity
Negativo	NaN
Igual a NaN	NaN
Igual a PositiveInfinity	PositiveInfinity

Ejemplos

El ejemplo siguiente ilustra la Log método.

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

Comentarios

El parámetro d se especifica como un número base 10.

Este método llama al entorno de ejecución de C subyacente y el resultado exacto o el intervalo de entrada válido pueden diferir entre diferentes sistemas operativos o arquitecturas.

Consulte también

Se aplica a

Compartir vía

Math.Log Método

Definición

Sobrecargas

Log(Double, Double)

Parámetros

Devoluciones

Ejemplos

Comentarios

Se aplica a

Log(Double)

Parámetros

Devoluciones

Ejemplos

Comentarios

Consulte también

Se aplica a

Recursos adicionales