8                                                            {
    9 
   14 
   16  t4s(
i, 
j, 
k, 
l) = t2s_1(
i, 
k) ^ t2s_2(
j, 
l);
 
   17 
   18  for (int ii = 0; ii != 3; ++ii)
   19    for (int jj = 0; jj != 3; ++jj)
   20      for (int kk = 0; kk != 3; ++kk)
   21        for (int ll = 0; ll != 3; ++ll) {
   22 
   23          auto small_eval = [&](auto n1, auto n2, auto n3, auto n4) {
   24            return t2s_1(n1, n3) * t2s_2(n2, n4);
   25          };
   26 
   27          const auto n1 = ii;
   28          const auto n2 = jj;
   29          const auto n3 = kk;
   30          const auto n4 = ll;
   31 
   33              small_eval(n1, n2, n3, n4) + small_eval(n2, n1, n3, n4) +
   34              small_eval(n1, n2, n4, n3) + small_eval(n2, n1, n4, n3);
   35 
   36          test_for_zero(t4s(ii, jj, kk, ll) - 
t, 
"t2s_1(i, k) ^ t2s_2(j, k)");
 
   37 
   38        }
   39}
FTensor::Index< 'i', SPACE_DIM > i
FTensor::Index< 'l', 3 > l
FTensor::Index< 'j', 3 > j
FTensor::Index< 'k', 3 > k
constexpr double t
plate stiffness
void test_for_zero(const T &t, const std::string &s)