Kernel weighting function
Instrumental to the sBF function. It returns weights used in the Nadaraya-Watson estimator.
K(u, method = "gaussian")distance from the origin.
type of kernel function. The default value is gaussian, other possible methods are: unifrom, epanechnikov, biweight, and triweight.
The domain of the kernel functions is centered at the origin and generally the weight value returned by the kernel decreases while the distance u from the origin increases.
Silverman, B. W. (1986) Density Estimation. London: Chapman and Hall.
sBF-package, sBF.