Hello, How can I translate a set of constraints into a "loop of variable fixations"? This is, in the example below I am trying to shift the Loop-constraint to a set of Fix-statements: * simple transportation model .. ; %Let Sources=10; %Let Plants=%Eval(&Sources.*2); Data Costs;   Do Source=1 To &Sources.;     Do Plant=1 To &Plants.;    Costs=Ranuni(1)*4+19; Output;     End;   End; Run; Data Demand;   Do Plant=1 To &Plants.;     Qty=Ranuni(1)*20+200; Output;   End; Run; Data Supply;   Do Source=1 To &Sources.;     Qty=Ranuni(1)*15+600; Output;   End; Run; Data Fixed;   Source=1; Plant=7; Fixed=50; Output;   Source=1; Plant=8; Fixed=50; Output;   Source=1; Plant=9; Fixed=50; Output;   Source=1; Plant=10; Fixed=50; Output;   Source=2; Plant=9; Fixed=50; Output;   Source=2; Plant=10; Fixed=50; Output; Run; Data Costs;   Merge Costs (in=inC) Fixed;   By Source Plant;   If inC; Run; Proc Optmodel;   Set <Num,Num> q_w;   Num Costs{q_w};   Num Fixed_F{q_w};   Read Data Costs Into q_w=[Source Plant] Costs=Costs Fixed_F=Fixed;   Set Sources=Setof{<q,w> in q_w} q;   Set Plants=Setof{<q,w> in q_w} w;   Num Demand{Plants};   Num Supply{Sources};   Read Data Demand Into [Plants=Plant] Demand=Qty;   Read Data Supply Into [Sources=Source] Supply=Qty;   Var X{Sources,Plants}>=0;   Con Cns1{q in Sources}:Sum{w in Plants}X[q,w]<=Supply ;   Con Cns2{w in Plants}:Sum{q in Sources}X[q,w]>=Demand ;   Con Loop{q in Sources, w in Plants:Fixed_F[q,w] ne .}:X[q,w]=Fixed_F[q,w]; * <-- equivalent "Fix"-Loop?;   *Fix X[1,6]=40;   Min Obj=Sum{q in Sources,w in Plants}X[q,w]*Costs[q,w];   Expand;   Solve;   Create Data Result From [Tail Head]={q in Sources, w in Plants} X; Run; Thanks & kind regards ... View more

Hello, I am playing around with the optmodel-network-examples a bit, and would like to add a binary variable. This is, you have to ship a fixed minimum amount from the sources to the sinks (or ship nothing). The example below works in principle, but I am worried about the "conditionally optimal" message. The critical restrictions are "balance" (the "<" sign) and "Lower_Upper_Flow". Is the syntax I am using all right? (The rationale I think is.) Let Fixed_Const=1e6; data garcs;    input _from_ $ _to_ $ _cost_ FIXED_QTY FIXED_COST Lower Upper; datalines; s1 d1 1 20 10 0 150 s1 d2 8 20 70 0 150 s2 d1 4 20 50 0 150 s2 d2 2 20 20 0 150 s2 d3 1 20 10 0 150 s3 d2 5 20 50 0 150 s3 d3 4 20 40 0 150 ; data gnodes;    input _node_ $ _sd_ ; datalines; s1  53 s2  21 s3  73 d1  -52 d2  -16 d3  -23 ; proc optmodel;    set <str> NODES;    num _sd_ {NODES} init 0;    read data gnodes into NODES=[_node_] _sd_;    set <str,str> ARCS;    num Lower {ARCS} init 0;    num Upper {ARCS};    num _capac_ {ARCS} init .;    num _cost_ {ARCS};    num FIXED_QTY {ARCS}, FIXED_COST {ARCS};    read data garcs nomiss into ARCS=[_from_ _to_] _cost_ FIXED_QTY FIXED_COST Lower Upper;    Print FIXED_QTY;    NODES = NODES union (union {<i,j> in ARCS} {i,j});    var Flow {<i,j> in ARCS}>=0;    var Flow_Fixed {<i,j> in ARCS} Binary;    min obj = sum {<i,j> in ARCS} (_cost_[i,j] * Flow[i,j] + FIXED_COST[i,j]*FIXED_QTY[i,j]*Flow_Fixed[i,j]);    con balance {i in NODES}: sum {<(i),j> in ARCS} (Flow[i,j] + FIXED_QTY[i,j]*Flow_Fixed[i,j])       - sum {<j,(i)> in ARCS} (Flow[j,i] + FIXED_QTY[j,i]*Flow_Fixed[j,i]) <= _sd_; * don't need to take all supply;    con Lower_Upper_Flow {<i,j> in ARCS}:Lower[i,j]<=Flow[i,j]+Flow_Fixed[i,j]*FIXED_QTY[i,j]<=Upper[i,j]; * is this ok?;    * or would something like this be better? and why?;    * -----------------------------------------------------------------;    * num excess = sum {i in NODES} _sd_;    *if (excess > 0) then do;       * change equality constraint to le constraint for supply nodes;      * for {i in NODES: _sd_ > 0} balance.lb = -infinity;    *end;    *else if (excess < 0) then do;     * change equality constraint to ge constraint for demand nodes;       *for {i in NODES: _sd_ < 0} balance.ub = infinity;    *end;    Con Con_Binary {<i,j> in ARCS}:Flow[i,j]<=&Fixed_Const.*Flow_Fixed[i,j]; * Flow has to be at least Fixed_Const (or nothing);    solve;    Print obj;    Print Flow Flow_Fixed; quit; Thanks&kind regards ... View more

Hello, how do you define a constraint for a specific set of variales (using "in" not GE or LE, etc.)? For example, instead of: Con Cns_Ex{c in Components:c="R2"}:Sum{p in Products} X *Qty[p,c]<=8; I would like something similar to: Con Cns_Ex{c in Components:c in ("R2", "R5")}:Sum{p in Products} X *Qty[p,c]<=8 Thanks&best regards ... View more

Hello, Is it possible to avoid zeros in input-datasets for proc optmodel? A simple example would look like this. In this case I would like to get rid of P1/R3, P2/R1, P3/R3 in "M_Qty". Data A;   Input Prod $ Comp $ Qty;   Datalines; P1 R1 0.8 P1 R2 0.2 P1 R3 0 P2 R1 0 P2 R2 0.5 P2 R3 0.5 P3 R1 0.2 P3 R2 0.8 P3 R3 0 ; Run; Data B;   Input Comp $ Price;   Datalines; R1 20 R2 30 R3 50 ; Run; Proc Optmodel;   Set <Str,Str> p_c;   Num M_Qty{p_c};   Read Data A Into p_c=[Prod Comp] M_Qty=Qty;   Set Products = SetOf{<p,c> in p_c} p;   Set Components = SetOf{<p,c> in p_c} c;   Num M_Price{Components};   Read Data B Into [Comp] M_Price=Price;    Var X{Products} >=0;   Con Cns1:Sum{p in Products,c in Components} X *M_Qty[p,c]>=5;   Con Cns2{c in Components:c="R1"}:Sum{p in Products} X *M_Qty[p,c]>=5;   Min Obj=Sum {p in Products, c in Components} M_Qty[p,c]*M_Price *X ;   Solve;   Print M_Qty; Quit; Thanks&kind regards ... View more