if TRUE, use the p-gaussian kernel function (see Francois et al. 2005). Else use the classic gaussian kernel, ie p-gaussian function with p=2 and sigma set to the maximal pairwise distance between elements of the data set.
Value
n x n kernel matrix.
References
Francois, D., Wertz, V. and Verleysen, M. (2005) About the locality of kernels in high-dimensional spaces. International Symposium on Applied Stochastic
Models and Data Analysis. 238-245.