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    std::log

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    <metanoindex/>

     
    C++
     
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    <tbody> </tbody>
    definiert in Header <cmath>
    float log( float arg );
    double log( double arg );
    long double log( long double arg );
    double log( Integral arg );
    		 (seit C++11)

    Computes the natural (base e) logarithm of arg.

    Parameter

    arg -
    Floating-Point-Wert
    Original:
    floating point value
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    Rückgabewert

    natural logarithm of arg.

    Domain-Fehler tritt auf, wenn arg negativ ist. NAN wird in diesem Fall wieder .
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    Domain error occurs if arg is negative. NAN is returned in that case.
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    Bereichs-Fehler tritt auf, wenn arg ist 0. -HUGE_VAL wird in diesem Fall wieder .
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    Range error occurs if arg is 0. -HUGE_VAL is returned in that case.
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    Beispiel

    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';
}

    Output: 

    8

    Siehe auch
    Renditen e an die angegebene Leistung (ex) angehoben
    Original:
    returns e raised to the given power (ex)
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    (Funktion) [edit]
    berechnet gemeinsamen (base 10) Logarithmus (log10(x))
    Original:
    computes common (base 10) logarithm (log10(x))
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    (Funktion) [edit]
    wirft eine Reihe an die angegebene Leistung (xy)
    Original:
    raises a number to the given power (xy)
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    (Funktion) [edit]
    komplexen natürlichen Logarithmus mit den Niederlassungen Schnitte entlang der negativen reellen Achse
    Original:
    complex natural logarithm with the branch cuts along the negative real axis
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    (Funktions-Template) [edit]
    wendet die Funktion std::log auf jedes Element valarray
    Original:
    applies the function std::log to each element of valarray
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    (Funktions-Template) [edit]