Function pack_eigensystem_from_columns

cpp_core/src/eigensolver.cpp:181–207

}

EigensystemResult pack_eigensystem_from_columns(
    int n,
    const std::vector<double>& eigenvalues,
    const std::vector<std::vector<Complex>>& eigenvectors
) {
    const int n_roots = static_cast<int>(eigenvalues.size());
    if (static_cast<int>(eigenvectors.size()) != n_roots) {
        throw std::invalid_argument("pack_eigensystem_from_columns: eigenvector count mismatch");
    }
    EigensystemResult out;
    out.n = n;
    out.eigenvalues_ha = eigenvalues;
    out.eigenvectors_col_major.assign(
        static_cast<std::size_t>(n * n_roots),
        Complex{0.0, 0.0}
    );
    for (int root = 0; root < n_roots; ++root) {
        const auto& col = eigenvectors[static_cast<std::size_t>(root)];
        if (static_cast<int>(col.size()) != n) {
            throw std::invalid_argument("pack_eigensystem_from_columns: eigenvector length mismatch");
        }
        for (int i = 0; i < n; ++i) {
            out.eigenvectors_col_major[static_cast<std::size_t>(i + n * root)] = col[static_cast<std::size_t>(i)];
        }
    }
    return out;
}

inline Complex& mat_ref(std::vector<Complex>& a, int n, int row, int col) {
    return a[static_cast<std::size_t>(row + n * col)];