Figure 8. Example of programming steps which can adjust the GAMS program exemplified in Figure 7 in order to impose variable or nonincreasing returns to scale.

1. Equations
2. Constr1(output,obs) DEA constraint for each output
3. Constr2(fixed,obs) DEA constraint for fixed inputs
4. Constr3(var,obs) DEA constraint for variable inputs
5. Constr4 DEA constraint for variable returns to scale;
6. Constr1(output,actobs).. sum(subobs,weight(subobs)*act (subobs,output)) =G= theta*act(actobs,output);
7. Constr2(fixed,actobs).. sum(subobs,weight(subobs)*act(subobs,fixed)) =L= act(actobs,fixed);
8. Constr3(var,actobs).. sum(subobs,weight(subobs)*act(subobs,var)) =E= lambda(actobs,var) *act(actobs,var);
9. Constr4.. sum(subobs,weight(subobs)) =E= 1;
10. Model tedea /constr1,constr2,const