According to the above index system, every index’s grades
of each kernel function are calculated. For each characteristic
parameter, the grades are shown in Tables 2–4. The kernel
functions orders in each table are linear function, polynomial
function, RBF function and sigmoid function. In these
tables, Sep. means the feature space separability, Sta. means
the stability, No. means the numbers of kernel parameters,
Acc.1 means the recognition accuracy rates when the samples
are 400, Acc.2 means the recognition accuracy rates when the
samples are 800.