请问这个表达式用lingo 怎么表达

sets:
row/1..5/:x,y,z,R;!此处可根据自身需要修改;
endsets
@for(row(k)|k#ge#2:z(k)=@sum(row(i)|i#le#k:y(i)*R(i))-@sum(row(i)|i#le#k-1:x(i)));