model diet.mod;
data diet2.dat;

param N symbolic in NUTR;
param nstart > 0;
param nstep > 0;
read N, nstart, nstep <- ;   # read data interactively

set N_MAX default {};
param N_obj {N_MAX};
param N_dual {N_MAX};
option solver_msg 0;

for {i in nstart .. 0 by -nstep} {
   let n_max[N] := i;
   solve;
   if solve_result = "infeasible" then {
      printf "--- infeasible at %d ---\n\n", i;
      break;
   }
   let N_MAX := N_MAX union {i};
   let N_obj[i] := Total_Cost;
   let N_dual[i] := Diet[N].dual;
}
display N_obj, N_dual;