Is linear kernel positive definite?
问题 In a lot of articles, the linear kernel (inner product of two matrices) is listed as positive definite however when I try it with a toy dataset, positive definiteness test returns negative result. I checked the MATLAB SVM function for linear kernel. The linear kernel function is one line command, K=(u*v') However after this step in the main svm_train function it does another operation using K, kx= (kx+kx')/2 + diag(1./boxconstraint) Where kx is K and diag(1./boxconstraint) is just a diagonal