Consider the approximation of a function
u(x) : Rd→R using the set of scattered nodes {xi }ni=1.
In the RBF approximation, a fixed radial function : Rd→R is chosen, i.e. (x)≡( x ) with
: [0,∞)→R. On using translates of this radial function with centres at xi , the following ansatz
is made [10]: