Definition: <m>sum{}{}{f®}</m>
<m>f®= 1/(1 + S^2*r^2)^2</m>, Cauchy kernel [McCormack and Sherstyuk 1998]
r - distance to a skeleton point
Call: hfConvPoint(x,vect,S,T);
Parameters:
x - point coordinates
vect - array of skeleton points' coordinates
S - array of kernel width control parameters for each point
T - threshold
Test file: convpoint.hf