arg

擷取一個複數的引數。

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

參數

• _ComplexNum
  要判斷引數的複數。

傳回值

複數的引數。

備註

這個引數為複雜向量以查看平面的正虛擬的軸進行的角度。 對於複雜數值 、+，這兩個引數的 arctan 相等 (*b/a)。*這個角度具有正數的觀點而言，在測量在需要大量虛擬的座標軸的向左移位和負的觀點而言，在測量順時針旋轉。 主值大於– pi 和小於或等於 +pi。

範例

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

int main( )
{
   using namespace std;
   double pi = 3.14159265359;

   // Complex numbers can be entered in polar form with
   // modulus and argument parameter inputs but are
   // stored in Cartesian form as real & imag coordinates
   complex <double> c1 ( polar ( 5.0 ) );   // Default argument = 0
   complex <double> c2 ( polar ( 5.0 , pi / 6 ) );
   complex <double> c3 ( polar ( 5.0 , 13 * pi / 6 ) );
   cout << "c1 = polar ( 5.0 ) = " << c1 << endl;
   cout << "c2 = polar ( 5.0 , pi / 6 ) = " << c2 << endl;
   cout << "c3 = polar ( 5.0 , 13 * pi / 6 ) = " << c3 << endl;

   // The modulus and argument of a complex number can be rcovered
   // using abs & arg member functions
   double absc1 = abs ( c1 );
   double argc1 = arg ( c1 );
   cout << "The modulus of c1 is recovered from c1 using: abs ( c1 ) = "
        << absc1 << endl;
   cout << "Argument of c1 is recovered from c1 using:\n arg ( c1 ) = "
        << argc1 << " radians, which is " << argc1 * 180 / pi
        << " degrees." << endl;

   double absc2 = abs ( c2 );
   double argc2 = arg ( c2 );
   cout << "The modulus of c2 is recovered from c2 using: abs ( c2 ) = "
        << absc2 << endl;
   cout << "Argument of c2 is recovered from c2 using:\n arg ( c2 ) = "
        << argc2 << " radians, which is " << argc2 * 180 / pi
        << " degrees." << endl;

   // Testing if the principal angles of c2 and c3 are the same
   if ( (arg ( c2 ) <= ( arg ( c3 ) + .00000001) ) || 
        (arg ( c2 ) >= ( arg ( c3 ) - .00000001) ) )
      cout << "The complex numbers c2 & c3 have the "
           << "same principal arguments."<< endl;
   else
      cout << "The complex numbers c2 & c3 don't have the "
           << "same principal arguments." << endl;
}

需求

標題: <complex>

命名空間: std