17 std::complex<double> output(0,0);
18 double xi2Norm= sqrt(std::pow(xi(0),2) + std::pow(xi(2),2));
20 double nuFactor= 1-nu;
25 output= output + xi(k)*xi(l)*std::numbers::pi/(2*std::pow(xi2Norm,3));
26 else if (k==1 && l==1)
27 output= output + std::numbers::pi/(2*xi2Norm);
30 std::list<int> ijkl{i,j,k,l};
31 int count= std::count(ijkl.begin(),ijkl.end(),1);
35 output= output - xi(i)*xi(j)*xi(k)*xi(l)/(2*nuFactor) * 3 * std::numbers::pi / (8*std::pow(xi2Norm,5));
37 output= output - 1.0/(2*nuFactor) * 3 * std::numbers::pi / (8*xi2Norm);
42 for(
const auto elem : ijkl)
44 output= output - temp/(2*nuFactor) * std::numbers::pi / (8*std::pow(xi2Norm,3));
47 return -output/(4*std::pow(std::numbers::pi,2)*
mu);