DuchonQ: Computes the semi-kernel of Duchon splines
Description
The function DuchonQ computes the semi-kernel of Duchon splines. This function is not intended to be used directly.Usage
DuchonQ(x,xk,m=2,s=0,symmetric=TRUE)
Value
The semi-kernel evaluated.References
Duchon, J. (1977) Splines minimizing rotation-invariant semi-norms in
Solobev spaces. in W. Shemp and K. Zeller (eds) Construction theory of
functions of several variables, 85-100, Springer, Berlin.