各位大神们，请问C++中complex.h怎么用？

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

int main(int argc, char *argv[])
{
    complex<double> a(1, 2), b(3, 4);

    cout << "a = " << a << ", b = " << b << endl;
    cout << "a + b = " << a + b << endl;
    cout << "a * b = " << a * b << endl;

    cout << "\nthe real part of a is " << real(a) << endl;
    cout << "the imaginary part of b is " << imag(b) << endl;
    cout << "the magnitude of a is " << abs(a) << endl;

    cout << "\ne^a = " << exp(a) << endl;
    cout << "ln(b) = " << log(b) << endl;

    return 0;
}