Kernels
=======

Methods:

.. method:: .matrix(x)
   
   Return the kernel matrix :math:`K_{ij} = k(x_i, x_j)`.

.. method:: .vector(a, x)
   
   Return the kernel vector :math:`K_i = k(x_i, a)`.

Linear Kernel
-------------

.. autoclass:: mlpy.KernelLinear

   .. math::
      
      K(x, x') = x \cdot x'

Gaussian Kernel
---------------

.. autoclass:: mlpy.KernelGaussian

   .. math::
      
      K(x, x') = e^{-\frac{\|x - x'\|}{2 \sigma^2}}

Polynomial Kernel
-----------------

.. autoclass:: mlpy.KernelPolynomial

   .. math::      
      
      K(x, x') = {(x \cdot x' + 1)}^d