{

std::vector<double> x, y, z;

double theta, r;

double z_inc = 4.0/99.0; double theta_inc = (8.0 * M_PI)/99.0;

for (double i = 0; i < 100; i += 1) {

theta = -4.0 * M_PI + theta_inc*i;

z.push_back(-2.0 + z_inc*i);

r = z[i]*z[i] + 1;

x.push_back(r * sin(theta));

y.push_back(r * cos(theta));

}

std::map<std::string, std::string> keywords;

keywords.insert(std::pair<std::string, std::string>("label", "parametric curve") );

plt::plot3(x, y, z, keywords);

plt::xlabel("x label");

plt::ylabel("y label");

plt::set_zlabel("z label"); // set_zlabel rather than just zlabel, in accordance with the Axes3D method

plt::legend();

plt::show();