dft_tools/test/triqs/arrays/group_indices.cpp

#include "./common.hpp"
#include <triqs/arrays.hpp>

using namespace triqs::arrays;
using namespace triqs::clef;

int main() {

 try {
  placeholder<0> i_;
  placeholder<1> j_;
  placeholder<2> k_;
  placeholder<3> l_;

  { // a simple test
   array<int, 4> A(2, 2, 2, 2);
   A(i_, j_, k_, l_) << i_ + 10 * j_ + 100 * k_ + 1000 * l_;
   TEST_ERR(A);
   TEST_ERR(group_indices_view(A, {0,1}, {2,3}));
  }

  // more complex : inversing a tensor product of matrices...
   matrix<double> B(2, 2), C(3, 3), Binv, Cinv;
   C(i_, j_) << 1.7 / (3.4 * i_ - 2.3 * j_ + 1);
   B(i_, j_) << 2 * i_ + j_;
   TEST_ERR(B);
   TEST_ERR(C);
   Binv = inverse(B);
   Cinv = inverse(C);
   TEST_ERR(Binv);
   TEST_ERR(Cinv);

   std::cerr << " --- (1) ---"<< std::endl;
   {
    array<double, 4> A(2, 3, 2, 3);
    A(i_, j_, k_, l_) << B(i_, k_) * C(j_, l_);

    TEST_ERR(A);

    auto M = make_matrix_view(group_indices_view(A, {0, 1}, {2, 3}));
    M = inverse(M);

    // checking
    array<double, 4> R(A.shape());
    R(i_, j_, k_, l_) << Binv(i_, k_) * Cinv(j_, l_);

    TEST_ERR(R);
    TEST_ERR(A);
    assert_all_close(R, A, 5.e-15);
   }

   std::cerr << " --- (2) ---"<< std::endl;
   {
    array<double, 4> A(2, 3, 2, 3, make_memory_layout(1, 0, 3, 2));
    A(i_, j_, k_, l_) << B(i_, k_) * C(j_, l_);

    TEST_ERR(A);

    auto M = make_matrix_view(group_indices_view(A, {0, 1}, {2, 3}));
    M = inverse(M);

    // checking
    array<double, 4> R(A.shape());
    R(i_, j_, k_, l_) << Binv(i_, k_) * Cinv(j_, l_);

    TEST_ERR(R);
    TEST_ERR(A);
    assert_all_close(R, A, 5.e-15);
   }
 
   std::cerr << " --- (3) ---"<< std::endl;
   {
    array<double, 4> A(2, 2, 3, 3, make_memory_layout(0, 2, 1, 3));
    A(i_, k_, j_, l_) << B(i_, k_) * C(j_, l_);

    TEST_ERR(A);

    auto M = make_matrix_view(group_indices_view(A, {0, 2}, {1, 3}));
    M = inverse(M);

    // checking
    array<double, 4> R(A.shape());
    R(i_, k_, j_, l_) << Binv(i_, k_) * Cinv(j_, l_);

    TEST_ERR(R);
    TEST_ERR(A);
    assert_all_close(R, A, 5.e-15);
   }
 }
 catch (std::exception const& e) {
  std::cerr << e.what() << std::endl;
 }
}