## GitHub

#### multi1a.run

File from Additional Scripts: Looping and Testing – 2

				
# ----------------------------------------
# DANTZIG-WOLFE DECOMPOSITION FOR
# MULTI-COMMODITY TRANSPORTATION
# ----------------------------------------

model multi1.mod;
data multi1.dat;

let nPROP := 0;
let price_convex := 1;
let {i in ORIG, j in DEST} price[i,j] := 0;

param phase symbolic, default "I";

option solver minos;
option omit_zero_rows 1;
option display_1col 10;
option display_eps .000001;

# ----------------------------------------------------------

problem Master: Artificial, Weight, Excess, Multi, Convex;
problem Sub: Artif_Reduced_Cost, Trans, Supply, Demand;

repeat { printf "\nPHASE %s -- ITERATION %d\n\n", phase, nPROP+1;

solve Sub;
printf "\n";
display Trans;

if phase = "I" then {
if Artif_Reduced_Cost >= - 0.00001 then {
printf "\n*** NO FEASIBLE SOLUTION ***\n";
break;
}
}
else {
if Reduced_Cost >= - 0.00001 then {
printf "\n*** OPTIMAL SOLUTION ***\n";
break;
}
};

let nPROP := nPROP + 1;
let {i in ORIG, j in DEST}
prop_ship[i,j,nPROP] := sum {p in PROD} Trans[i,j,p];
let prop_cost[nPROP] :=
sum {i in ORIG, j in DEST, p in PROD} cost[i,j,p] * Trans[i,j,p];

solve Master;
printf "\n";
display Weight;

if phase = "I" then {
display Multi.dual;
display {i in ORIG, j in DEST}
limit[i,j] - sum {k in 1..nPROP} prop_ship[i,j,k] * Weight[k];

if Excess <= 0.00001 then {
printf "\nSETTING UP FOR PHASE II\n\n";
let phase := "II";

problem Master;
drop Artificial; restore Total_Cost; fix Excess;
problem Sub;
drop Artif_Reduced_Cost; restore Reduced_Cost;

#  problem Master; show obj; solve;
solve Master;
printf "\n";
display Weight; display Multi.dual; display Multi.slack;
};
};

let {i in ORIG, j in DEST} price[i,j] := Multi[i,j].dual;
let price_convex := Convex.dual;
};

# ----------------------------------------------------------

printf "\nPHASE III\n\n";

problem MasterIII: Opt_Cost, Trans, Supply, Demand, Opt_Multi;

let {i in ORIG, j in DEST}
opt_ship[i,j] := sum {k in 1..nPROP} prop_ship[i,j,k] * Weight[k];

solve MasterIII;
printf "\n";
display Trans;