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std::log

De cppreference.com
< cpp‎ | numeric‎ | math

 
 
Bibliothèque Numerics
Fonctions mathématiques courantes
Virgule flottante environnement
Nombres complexes
Tableaux numériques
La génération de nombres pseudo-aléatoires
Moment de la compilation arithmétique rationnelle (C++11)
Génériques des opérations numériques
Original:
Generic numeric operations
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iota (C++11)
accumulate
inner_product
adjacent_difference
partial_sum
 
Fonctions mathématiques courantes
{{{1}}}
Original:
{{{2}}}
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Fonctions
Original:
Functions
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Opérations de base
Original:
Basic operations
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remainder (C++11)
remquo (C++11)
fma (C++11)
fmax (C++11)
fmin (C++11)
fdim (C++11)
nan
nanf
nanl
(C++11)
(C++11)
(C++11)
Les fonctions exponentielles
Original:
Exponential functions
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exp
exp2 (C++11)
expm1 (C++11)
log
log10
log1p (C++11)
log2 (C++11)
Les fonctions de puissance
Original:
Power functions
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sqrt
cbrt (C++11)
hypot (C++11)
pow
Les fonctions trigonométriques et hyperboliques
Original:
Trigonometric and hyperbolic functions
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sinh
cosh
tanh
asinh (C++11)
acosh (C++11)
atanh (C++11)
{{{1}}}
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{{{2}}}
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Erreur fonctions et gamma
Original:
Error and gamma functions
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erf (C++11)
erfc (C++11)
lgamma (C++11)
tgamma (C++11)
Entier le plus proche opérations en virgule flottante
Original:
Nearest integer floating point operations
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ceil
floor
round
lround
llround
(C++11)
(C++11)
(C++11)
trunc (C++11)
nearbyint (C++11)
rint
lrint
llrint
(C++11)
(C++11)
(C++11)
Flottant fonctions de manipulation de points
Original:
Floating point manipulation functions
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ldexp
scalbn
scalbln
(C++11)
(C++11)
ilogb (C++11)
logb (C++11)
frexp
modf
nextafter
nexttoward
(C++11)
(C++11)
copysign (C++11)
Classification / Comparaison
Original:
Classification/Comparison
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fpclassify (C++11)
isfinite (C++11)
isinf (C++11)
isnan (C++11)
isnormal (C++11)
signbit (C++11)
isgreater (C++11)
isgreaterequal (C++11)
isless (C++11)
islessequal (C++11)
islessgreater (C++11)
isunordered (C++11)
Macro constantes
Original:
Macro constants
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FP_NORMAL
FP_SUBNORMAL
FP_ZERO
FP_INFINITE
FP_NAN
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
</div>
 
</div>
Defined in header <cmath>
float       log( float arg );
double      log( double arg );
long double log( long double arg );
double      log( Integral arg );
(depuis C++11)
Calcule le naturel (base e) logarithme de arg .
Original:
Computes the natural (base e) logarithm of arg.
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Sommaire

[modifier] Paramètres

arg -
valeur du point flottant
Original:
floating point value
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[modifier] Retourne la valeur

logarithme naturel de arg .
Original:
natural logarithm of arg.
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Erreur de domaine se produit si arg est négatif. NAN est retourné dans ce cas .
Original:
Domain error occurs if arg is negative. NAN is returned in that case.
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Erreur d'intervalle se produit si arg est 0. -HUGE_VAL est retourné dans ce cas .
Original:
Range error occurs if arg is 0. -HUGE_VAL is returned in that case.
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[modifier] Exemple

Le code suivant calcule le binaire (base 2') avec l'aide de logarithme logarithme naturel .
Original:
The following code computes the binary (base 2) logarithm with help of natural logarithm.
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#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';
}

Résultat :

8

[modifier] Voir aussi

retours e à la puissance donnée (ex)
Original:
returns e raised to the given power (ex)
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(fonction) [edit]
calcule commune (base 10) Logarithme (log10(x))
Original:
computes common (base 10) logarithm (log10(x))
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(fonction) [edit]
soulève un certain nombre à la puissance donnée (xy)
Original:
raises a number to the given power (xy)
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(fonction) [edit]
complexe logarithme naturel avec les coupures de ramification le long de l'axe réel négatif
Original:
complex natural logarithm with the branch cuts along the negative real axis
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(fonction générique) [edit]
applique la fonction std::log à chaque élément de valarray
Original:
applies the function std::log to each element of valarray
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(fonction générique) [edit]