var_nodes.m

function [var]=var_nodes(first,last,number) 
var=[]; 
if number==6 
    tp(1)=first; 
    tp(2)=first+1; 
    for k=first+2:last/2-1 
       tp(3) =k; 
       for q=k+1:last/2 
          tp(4)=q;  
          for tt=q+1:last-1 
          tp(5)=tt; tp(6)=last; 
          var=[var;tp]; 
          end 
       end 
    end 
end 
 
 
if number==5 
    tp(1)=first;     
    tp(2)=first+1; 
    for k=first+2:last/2 
       tp(3) =k; 
       for q=k+1:last-1 
          tp(4)=q;tp(5)=last; 
          var=[var;tp]; 
       end 
    end 
end 
 
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if number==4 
    tp(1)=first; 
    for k=first+1:last-2 
       tp(2) =k; 
       for q=k+1:last-1 
          tp(3)=q;tp(4)=last; 
          var=[var;tp]; 
       end 
    end 
end 
 
 
if number==3 
       tp(1) =first; 
       for q=first+1:last-1 
          tp(2)=q; tp(3)=last; 
          var=[var;tp]; 
       end 
 
end 
 
if number==2 
       tp(1) =first;tp(2)=last;  
       var=[var;tp]; 
end