{
	A set of randomly located points at known positions to be
	interpolated by gensurf.
}
				{ The following are our known point values }
point(i,j) = select( i*3+j+1,
		2, 1, 5,		{ x0, y0, z0 }
		3.7, 1, 1,
		4.2, 2.5, 2,
		3,7, 2.5, 4,
		2, 2.5, 3,
		2, 3.5, 2
	);

Npoints = 6;				{ Number of points in above }

sq(x) : x*x;

Recip(x) : if( x, 1/x, 1e10 );

Sum(f,x,y,n) = if(n-.5, f(x,y,n-1)+Sum(f,x,y,n-1), 0);

weight(x,y,i) = Recip(sq(x-point(i,0)) + sq(y-point(i,1)));

wval(x,y,i) = weight(x,y,i) * point(i,2);

sheight(x,y) = Sum(wval,x,y,Npoints) / Sum(weight,x,y,Npoints);
