function [cdu] = comps(i)   

    a = [0,10,50,100,200,300,500,1000; 0,1,1.8,2.4,3.2,3.8,4.8,6.8];
    a(1,:)=a(1,:)/500;
    a(2,:)=a(2,:)*1.1;
    
    k = zeros(7,1);
    for l = 1:7,
       k(l) = (a(2,l+1) - a(2,l))/(a(1,l+1) - a(1,l));
    end
    
	si = sign(i);
	i = abs(i);
		
	if(i < a(1,2)) 
        du = k(1)*i;
    elseif(i < a(1,3)) 
        du = k(2)*(i-a(1,2)) + a(2,2);
    elseif(i < a(1,4)) 
        du = k(3)*(i-a(1,3)) + a(2,3);
    elseif(i < a(1,5)) 
        du = k(4)*(i-a(1,4)) + a(2,4);
    elseif(i < a(1,6)) 
        du = k(5)*(i-a(1,5)) + a(2,5);
    elseif(i < a(1,7)) 
        du = k(6)*(i-a(1,6)) + a(2,6);				
    else
        du = k(7)*(i - a(1,7)) + a(2,7);
    end
	
    if (du < 0)
        du = 0;
    end
    
	cdu = si*du;
end