DOC fix polynomial kernel formula
@@ -1202,7 +1202,7 @@ def polynomial_kernel(X, Y=None, degree=3, gamma=None, coef0=1):
"""
Compute the polynomial kernel between X and Y.
- :math:`K(X, Y) = (gamma <X, Y> + coef0)^degree`
+ :math:`K(X, Y) = (gamma <X, Y> + coef0)^{degree}`
Read more in the :ref:`User Guide <polynomial_kernel>`.
