Merge pull request scikit-learn#783 from dwf/svm_docs_minor

Minor tweaks to the SVM documentation

Author: agramfort

doc/modules/svm.rst

@@ -396,10 +396,10 @@ The *kernel function* can be any of the following:
   * polynomial: :math:`(\gamma <x, x'> + r)^d`. `d` is specified by
     keyword ``degree``, `r` by ``coef0``.
 
-  * rbf (:math:`exp(-\gamma |x-x'|^2), \gamma > 0`). :math:`\gamma` is
+  * rbf (:math:`\exp(-\gamma |x-x'|^2), \gamma > 0`). :math:`\gamma` is
     specified by keyword ``gamma``.
 
-  * sigmoid (:math:`tanh(<x_i,x_j> + r)`), where `r` is specified by
+  * sigmoid (:math:`\tanh(<x_i,x_j> + r)`), where `r` is specified by
     ``coef0``.
 
 Different kernels are specified by keyword kernel at initialization::

sklearn/svm/classes.py

@@ -149,6 +149,13 @@ class SVC(BaseLibSVM, ClassifierMixin):
 
     The multiclass support is handled according to a one-vs-one scheme.
 
+    For details on the precise mathematical formulation of the provided
+    kernel functions and how `gamma`, `coef0` and `degree` affect each,
+    see the corresponding section in the narrative documentation:
+    :ref:`svm_kernels`.
+
+    .. The narrative documentation is available at http://scikit-learn.org/
+
     Parameters
     ----------
     C : float or None, optional (default=None)