log

Retourne le logarithme népérien d'un nombre complexe.

template<class Type>
   complex<Type> log(
      const complex<Type>& _ComplexNum
   );

Paramètres

• _ComplexNum
  Le nombre complexe dont le logarithme népérien est déterminé.

Valeur de retour

Le nombre complexe qui est le logarithme népérien du nombre complexe d'entrée.

Notes

Les coupes de branche sont le long de le vrai axe négatif.

Exemple

// complex_log.cpp
// compile with: /EHsc
#include <vector>
#include <complex>
#include <iostream>

int main() {
   using namespace std;
   double pi = 3.14159265359;
   complex <double> c1 ( 3.0 , 4.0 );
   cout << "Complex number c1 = " << c1 << endl;

   // Values of log of a complex number c1
   complex <double> c2 = log ( c1 );
   cout << "Complex number c2 = log ( c1 ) = " << c2 << endl;
   double absc2 = abs ( c2 );
   double argc2 = arg ( c2 );
   cout << "The modulus of c2 is: " << absc2 << endl;
   cout << "The argument of c2 is: "<< argc2 << " radians, which is " 
        << argc2 * 180 / pi << " degrees." << endl << endl; 

   // log of the standard angles  
   // in the first two quadrants of the complex plane
   vector <complex <double> > v1;
   vector <complex <double> >::iterator Iter1;
   complex <double> vc1  ( polar (1.0, pi / 6) );
   v1.push_back( log ( vc1 ) );
   complex <double> vc2  ( polar (1.0, pi / 3) );
   v1.push_back( log ( vc2 ) );
   complex <double> vc3  ( polar (1.0, pi / 2) );
   v1.push_back( log ( vc3) );
   complex <double> vc4  ( polar (1.0, 2 * pi / 3) );
   v1.push_back( log ( vc4 ) );
   complex <double> vc5  ( polar (1.0, 5 * pi / 6) );
   v1.push_back( log ( vc5 ) );
   complex <double> vc6  ( polar (1.0,  pi ) );
   v1.push_back( log ( vc6 ) );

   cout << "The complex components log (vci), where abs (vci) = 1 "
        << "\n& arg (vci) = i * pi / 6 of the vector v1 are:\n" ;
   for ( Iter1 = v1.begin() ; Iter1 != v1.end() ; Iter1++ )
      cout << *Iter1 << " " << endl;
}

Résultat de l'exemple

Complex number c1 = (3,4)
Complex number c2 = log ( c1 ) = (1.60944,0.927295)
The modulus of c2 is: 1.85746
The argument of c2 is: 0.522706 radians, which is 29.9489 degrees.

The complex components log (vci), where abs (vci) = 1 
& arg (vci) = i * pi / 6 of the vector v1 are:
(0,0.523599) 
(0,1.0472) 
(0,1.5708) 
(0,2.0944) 
(0,2.61799) 
(0,-3.14159) 

Configuration requise

en-tête : <complex>

l'espace de noms : DST