Method trace

Core/VirtualQuantumProcessor/DensityMatrix/DensityMatrix.cpp:806–818

template <typename data_t>
std::complex<double> DensityMatrix<data_t>::trace()
{
    double val_real = 0.;
    double val_imag = 0.;

    for (size_t k = 0; k < m_rows; ++k)
    {
        val_real += std::real(VectorMatrix<data_t>::m_data[k * m_rows + k]);
        val_imag += std::imag(VectorMatrix<data_t>::m_data[k * m_rows + k]);
    }

    return std::complex<double>(val_real, val_imag);
}

template class QPanda::DensityMatrix<double>;
template class QPanda::DensityMatrix<float>;