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      std::log

      De cppreference.com
      < cpp‎ | numeric‎ | math

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      C++
       
      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
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      Functions
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      Opérations de base
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      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
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      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
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      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
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      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
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      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
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      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
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      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
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      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>
      Déclaré dans l'en-tête <cmath>
      float       log(float arg );
      double      log(double arg );
      longdouble log(longdouble 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]
      Récupérée de « https://fr.cppreference.com/mwiki/index.php?title=cpp/numeric/math/log&oldid=48859 »
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