[Help-glpk] Re: ordered and ord in MathProg?

[Noli Sicad]

I search the archive regarding this topic -ord

Andrew's reply below but hard to understand.

http://www.mail-archive.com/address@hidden/msg01281.html

Anyway, I tried to reformulate based on how I understand it. Revised
model below.

It is still not working.

Noli

~~~~~~~~~~

# mrp.mod
# AMPL: Data for mrp formulation

set PP; # ordered;              # Set of SKU Numbers
set TT; # ordered;              # Set of Time Buckets

param ord1{i in PP, s in TT};
param ord2{i in PP, t in TT};

param P integer := card(PP); # Number of SKUs
param T integer := card(TT); # Number of Time Buckets
param M  >= 0;               # Large Number

param LT {PP} integer;      # Lead Time
param R  {PP,PP} integer;   # number of i to make one j
param D {PP, TT} integer;   # External Demand for an item in a period
param I {PP} integer;       # Beginning Inventory
param LS {PP} integer;      # Lot Size


var d {PP, TT} binary;      # production indicator
var x {PP, TT} >=0;         # number of SKUs to produce

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

minimize objective: sum {i in PP, t in TT}
                     (T-ord2(t)+1) * x[i,t];

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

subject to MaterialRequirement {i in PP, t in TT}:
  (sum {s in TT: ord1(s) <= ord2(t)-LT[i] } x[i,s] )
   + I[i]
   - sum {s in TT: ord1(s)<=ord2(t)}
         (D[i,s] + sum {j in PP} R[i,j]* x[j,s])
   >= 0;

subject to LotSize {i in PP, t in TT}:
   x[i,t] - d[i,t]*LS[i] >= 0;

subject to ProductionIndicator {i in PP, t in TT}:
   d[i,t] - x[i,t]/M >=0;

Error,

GLPSOL: GLPK LP/MIP Solver, v4.42
Parameter(s) specified in the command line:
 --cover --clique --gomory --mir -m mrp_c3.mod
Reading model section from mrp_c3.mod...
mrp_c3.mod:28: function ord2 unknown
Context:  minimize objective : sum { i in PP , t in TT } ( T - ord2 (
MathProg model processing error
>Exit code: 1    Time: 0.206