std::log10(std::complex)

#include <iostream>
#include <cmath>
#include <complex>
 
int main()
{
    std::complex<double> z(0, 1); // // r = 0, θ = pi/2
    std::cout << "2*log10" << z << " = " << 2.*std::log10(z) << '\n';
 
    std::complex<double> z2(sqrt(2)/2, sqrt(2)/2); // r = 1, θ = pi/4
    std::cout << "4*log10" << z2 << " = " << 4.*std::log10(z2) << '\n';
 
    std::complex<double> z3(-100, 0); // r = 100, θ = pi
    std::cout << "log10" << z3 << " = " << std::log10(z3) << '\n';
    std::complex<double> z4(-100, -0.0); // 切割的另一侧
    std::cout << "log10" << z4 << " (the other side of the cut) = "
              << std::log10(z4) << '\n'
              << "(note: pi/log(10) = " << acos(-1)/log(10) << ")\n";
}