Polynomial Kernel FunctionRefers to a kernel function expressed in polynomial form. It is a non-standard kernel function suitable for orthogonal normalized data. Its specific form is shown in the figure.

$latex K(\chi_i,\chi_j)=( \gamma X_i^TX_j + r)^d,\gamma > 0$

In machine learning, a polynomial kernel is a kernel function commonly used in support vector machines (SVMs) and other kernelized models that represents the similarity between vectors (training samples) in feature space and a polynomial of the original variables, allowing the learning of nonlinear models.

Common kernel functions are:

1. Linear kernel function;
2. Polynomial kernel function;
3. Gaussian (RBF) kernel function;
4. sigmoid kernel function;
5. Custom kernel function.

Parent word: kernel function