Selecting the optimal parameters for support vector machine (SVM) has long been a hot research topic. Aiming for support vector classification/regression (SVC/SVR) with the radial basis function (RBF) kernel

we summarize the rough line rule of the penalty parameter and kernel width

and propose a novel linear search method to obtain these two optimal parameters. We use a direct-setting method with thresholds to set the epsilon parameter of SVR. The proposed method directly locates the right search field

which greatly saves computing time and achieves a stable

high accuracy. The method is more competitive for both SVC and SVR. It is easy to use and feasible for a new data set without any adjustments

since it requires no parameters to set.