// A short example to show how to declare a complex number in C++.

#include <complex>
#include <iostream>
using namespace std;

int main( )
{
   double_complex x;

   // Set x equal to the square root of -1.  Notice that we cannot simply
   // write sqrt(-1) because that would use the ordinary sqrt function.
   // The notaton (double_complex) -1 is used to convert -1 to
   // a double_complex data type, and then the complex version of sqrt
   // will be used.
   x = sqrt( (double_complex) -1);

   // Complex numbers can be printed.  This one will print as (0,-1),
   // which means that its real part is zero and its imaginary part is -1.
   cout << x << endl;

   return 0; // Tell the operating system that the program succeeded.
}