Function contraction_ij

cpp_core/src/paw_projector.cpp:298–315

}

double contraction_ij(const std::vector<std::vector<double>>& a, const std::vector<std::vector<double>>& b) {
    const int n = static_cast<int>(a.size());
    if (n <= 0 || static_cast<int>(b.size()) != n) {
        throw std::invalid_argument("contraction_ij: matrix size mismatch");
    }
    double sum = 0.0;
    for (int i = 0; i < n; ++i) {
        if (static_cast<int>(a[static_cast<std::size_t>(i)].size()) != n
            || static_cast<int>(b[static_cast<std::size_t>(i)].size()) != n) {
            throw std::invalid_argument("contraction_ij: matrix size mismatch");
        }
        for (int j = 0; j < n; ++j) {
            sum += a[static_cast<std::size_t>(i)][static_cast<std::size_t>(j)]
                 * b[static_cast<std::size_t>(i)][static_cast<std::size_t>(j)];
        }
    }
    return sum;
}

std::vector<double> build_normalized_gaussian_shape(
    const std::vector<double>& r_grid,