for(int i=2;i<5;i++)
{
spline ix:=1!Col(5) iy:=1!(Col(1), Col($(i))) ox:=2!<new>;  
//Col(5) is X for anchor points, create the Y values for anchor points by spline 
interp1 ix:=1!Col(1) iy:=(1!Col(5), 2!Col($(i-1))) ox:=3!<new>; 
//bridge the anchor point to baseine, using original X as baseline X  
range a1=1!Col($(i));
range a2=3!Col($(i-1));   // substract the curve by baseline.
a1=a1-a2;
};