Definition: <m>Sum{}{}{f®}-T</m>,
<m>f®=delim{lbrace}{matrix{3}{1}3_r_d_0_r_d}{ }</m>
r - distance to the given point

Call: hfMetaball(x,x0,y0,z0,b,d,T);

Parameters:

x - point coordinates

x0,y0,z0 - arrays of mataball centers

b - array of b coefficients

d - array of d radii of influence

T - threshold value

Test file: metaball.hf