Symmetric Bilinear Form ======================= To find the distinct roots :math:`\{z_i\}_{i=1}^n` and corresponding multiplicities :math:`\{m_i\}` of the given function :math:`f(z)` within the given contour :math:`C` use is made of the fact that .. math:: \frac{1}{2\pi i} \int_C \phi(z)\psi(z) \frac{f'(z)}{f(z)} dz = \sum_{i=1}^n m_i \phi(z_i) \psi(z_i) In `cxroots` the left hand side is computed using the function :func:`~cxroots.root_counting.prod`. .. autofunction:: cxroots.root_counting.prod