Gaussian Radial Basis Function Kernel

Definition

$K({\mathbf{x}}_i,{\mathbf{x}}_j)=\exp \left(-\frac{||{\mathbf{x}}_i-{\mathbf{x}}_j|{|}^2}{2{\sigma }^2}\right)=\exp \left(-\gamma ||{\mathbf{x}}_i-{\mathbf{x}}_j|{|}^2\right)$