transport7.cpp
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26 #include "gams.h"
27 #include <vector>
28 #include <iostream>
29 
30 using namespace gams;
31 using namespace std;
32 
34 string getModelText()
35 {
36  return " Sets \n"
37  " i canning plants / seattle, san-diego / \n"
38  " j markets / new-york, chicago, topeka / ; \n"
39  " \n"
40  "Parameters \n"
41  " a(i) capacity of plant i in cases \n"
42  " / seattle 350 \n"
43  " san-diego 600 / \n"
44  " \n"
45  " b(j) demand at market j in cases \n"
46  " / new-york 325 \n"
47  " chicago 300 \n"
48  " topeka 275 / ; \n"
49  " \n"
50  "Table d(i,j) distance in thousands of miles \n"
51  " new-york chicago topeka \n"
52  " seattle 2.5 1.7 1.8 \n"
53  " san-diego 2.5 1.8 1.4 ; \n"
54  " \n"
55  "Scalar f freight in dollars per case per thousand miles /90/ ;\n"
56  "Scalar bmult demand multiplier /1/; \n"
57  " \n"
58  "Parameter c(i,j) transport cost in thousands of dollars per case ; \n"
59  " \n"
60  " c(i,j) = f * d(i,j) / 1000 ; \n"
61  " \n"
62  "Variables \n"
63  " x(i,j) shipment quantities in cases \n"
64  " z total transportation costs in thousands of dollars ; \n"
65  " \n"
66  "Positive Variable x ; \n"
67  " \n"
68  "Equations \n"
69  " cost define objective function \n"
70  " supply(i) observe supply limit at plant i \n"
71  " demand(j) satisfy demand at market j ; \n"
72  " \n"
73  "cost .. z =e= sum((i,j), c(i,j)*x(i,j)) ; \n"
74  " \n"
75  "supply(i) .. sum(j, x(i,j)) =l= a(i) ; \n"
76  " \n"
77  "demand(j) .. sum(i, x(i,j)) =g= bmult*b(j) ; \n"
78  " \n"
79  "Model transport /all/ ; \n";
80 }
81 
89 int main(int argc, char* argv[])
90 {
91  cout << "---------- Transport 7 --------------" << endl;
92 
93  try {
94  GAMSWorkspaceInfo wsInfo;
95  if (argc > 1)
96  wsInfo.setSystemDirectory(argv[1]);
97  GAMSWorkspace ws(wsInfo);
98  GAMSCheckpoint cp = ws.addCheckpoint();
99 
100  // initialize a GAMSCheckpoint by running a GAMSJob
101  GAMSJob t7 = ws.addJobFromString(getModelText());
102  t7.run(cp);
103 
104  // create a GAMSModelInstance and solve it multiple times with different scalar bmult
106  GAMSParameter bmult = mi.syncDb().addParameter("bmult", 0, "demand multiplier");
107  GAMSOptions opt = ws.addOptions();
108  opt.setAllModelTypes("cplex");
109 
110  // instantiate the GAMSModelInstance and pass a model definition and GAMSModifier to declare bmult mutable
111  mi.instantiate("transport use lp min z", opt, GAMSModifier(bmult));
112 
113  bmult.addRecord().setValue(1.0);
114  vector<double> bmultlist = { 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3 };
115 
116  for (double b : bmultlist) {
117  bmult.firstRecord().setValue(b);
118  mi.solve();
119  cout << "Scenario bmult=" << b << ":" << endl;
120  cout << " Modelstatus: " << mi.modelStatusAsString() << endl;
121  cout << " Solvestatus: " << mi.solveStatusAsString() << endl;
122  cout << " Obj: " << mi.syncDb().getVariable("z").findRecord().level() << endl;
123  }
124 
125  // create a GAMSModelInstance and solve it with single links in the network blocked
126  mi = cp.addModelInstance();
127 
128  GAMSVariable x = mi.syncDb().addVariable("x", 2, GAMSEnum::VarType::Positive, "");
129  GAMSParameter xup = mi.syncDb().addParameter("xup", 2, "upper bound on x");
130 
131  // instantiate the GAMSModelInstance and pass a model definition and GAMSModifier to declare upper bound of X mutable
132  mi.instantiate("transport use lp min z", GAMSModifier (x, GAMSEnum::SymbolUpdateAction::Upper, xup));
133 
134  for (GAMSSetRecord i : t7.outDB().getSet("i")) {
135  for (GAMSSetRecord j : t7.outDB().getSet("j")) {
136  xup.clear();
137  xup.addRecord(i.key(0), j.key(0)).setValue(0);
138  mi.solve();
139  cout << "Scenario link blocked=" << i.key(0) << "-" << j.key(0) << endl;
140  cout << " Modelstatus: " << mi.modelStatusAsString() << endl;
141  cout << " Solvestatus: " << mi.solveStatusAsString() << endl;
142  cout << " Obj: " << mi.syncDb().getVariable("z").findRecord().level() << endl;
143  }
144  }
145 
146  } catch (GAMSException &ex) {
147  cout << "GAMSException occured: " << ex.what() << endl;
148  } catch (exception &ex) {
149  cout << ex.what() << endl;
150  }
151 
152  return 0;
153 }
void setSystemDirectory(std::string systemDir)
GAMSDatabase syncDb()
void instantiate(const std::string &modelDefinition, const gams::GAMSOptions &options, const std::vector< gams::GAMSModifier > &modifiers={ })
void solve(GAMSEnum::SymbolUpdateType updateType, std::ostream &output, GAMSModelInstanceOpt miOpt)
GAMSVariable getVariable(const std::string &name)
void setAllModelTypes(const std::string &solver)
GAMSVariable addVariable(const std::string &name, const int dimension, const GAMSEnum::VarType varType, const std::string &explanatoryText="")
GAMSParameterRecord addRecord(const std::vector< std::string > &keys)
GAMSDatabase outDB()
GAMSVariableRecord findRecord(const std::vector< std::string > &keys)
std::string solveStatusAsString()
GAMSParameter addParameter(const std::string &name, const int dimension, const std::string &explanatoryText="")
GAMSParameterRecord firstRecord(const std::vector< std::string > &slice)
std::string modelStatusAsString()
GAMSSet getSet(const std::string &name)
GAMSModelInstance addModelInstance(const std::string &modelInstanceName="")
void setValue(const double val)
string getModelText()
Get model as string.
Definition: transport7.cpp:34