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      std::log

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      Biblioteca numéricos
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      Genéricos operações numéricas
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      Generic numeric operations
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      Funções matemáticas comuns
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      Operações básicas
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      Número inteiro mais próximo de operações de ponto flutuante
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      Nearest integer floating point operations
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      Flutuando funções de manipulação de pontos
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      Floating point manipulation functions
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      Constantes de macros
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      Macro constants
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      <tbody> </tbody>
      Definido no cabeçalho <cmath>
      float log( float arg );
      double log( double arg );
      long double log( long double arg );
      double log( Integral arg );
      		 (desde C++11)

      Computes the natural (base e) logarithm of arg.

      Parâmetros

      arg -
      flutuando valor de ponto
      Original:
      floating point value
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      Valor de retorno

      natural logarithm of arg.

      Erro de domínio ocorre se arg é negativo. NAN é devolvido em caso.
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      Domain error occurs if arg is negative. NAN is returned in that case.
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      Faixa de erro ocorre se arg é 0. -HUGE_VAL é devolvido em caso.
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      Range error occurs if arg is 0. -HUGE_VAL is returned in that case.
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      Exemplo

      The following code computes the binary (base 2) logarithm with help of natural logarithm.

      #include <cmath>
#include <iostream>
 
int main()
{
    double base = 2.0;
    double arg  = 256.0;
    double result = std::log(arg) / std::log(base);
 
    std::cout << result << '\n';
}

      Saída: 

      8

      Veja também
      retorna e elevado à potência dada (ex)
      Original:
      returns e raised to the given power (ex)
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      (função) [edit]
      calcula comum (base 10) logaritmo (log10(x))
      Original:
      computes common (base 10) logarithm (log10(x))
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      (função) [edit]
      levanta uma série para o poder dado (xy)
      Original:
      raises a number to the given power (xy)
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      (função) [edit]
      logaritmo natural complexo com os cortes ao longo do ramo negativo do eixo real
      Original:
      complex natural logarithm with the branch cuts along the negative real axis
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      (modelo de função) [edit]
      aplica-se a std::log função de cada elemento de valarray
      Original:
      applies the function std::log to each element of valarray
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      (modelo de função) [edit]