核函数类型

核函数公式

Linear Kernel

$K\left(X,X_i\right)=\left(X^{\text{T}}{X}_i\right)$

Polynomial Kernel

$K\left(X,X_i\right)={\left(\left(X^{\text{T}}{X}_i\right)+1\right)}^d$

Radial based Kernel (RBF)

$K\left(X,X_i\right)=\exp \left(-\gamma {\Vert x-x_i\Vert }^2\right)$

Sigmoid Kernel

$K\left(X,X_i\right)=\tanh \left(x^{\text{T}}{x}_i\right)+b$