Exponential RBF kernel. The outputs of the exponential radial basis function kernel as functions of the Euclidean distance between vectors. Four functions are depicted in dashed-double-dotted-blue, long-dashed-red, dashed-green, and dotted-purple curves, corresponding to the cases where the sigma is 0.5, 0.707, 1.0, and 2.0 respectively.
Land et al. BMC Systems Biology 2011 5(Suppl 3):S13 doi:10.1186/1752-0509-5-S3-S13