transport6.cpp
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26 #include "gams.h"
27 #include <vector>
28 #include <iostream>
29 #include <thread>
30 #include <mutex>
31 
32 using namespace gams;
33 using namespace std;
34 
36 void runScenario(GAMSWorkspace* ws, const GAMSCheckpoint& cp, mutex* ioMutex, double b)
37 {
38  auto t6 = ws->addJobFromString("bmult=" + to_string(b) + "; solve transport min z use lp; ms=transport.modelstat; ss=transport.solvestat;", cp);
39  t6.run();
40 
41  // we need to make the ouput a critical section to avoid messed up report information
42  lock_guard<mutex> lck(*ioMutex);
43  cout << "Scenario bmult=" << b << ":" << endl;
44  cout << " Modelstatus: " << t6.outDB().getParameter("ms").findRecord().value() << endl;
45  cout << " Solvestatus: " << t6.outDB().getParameter("ss").findRecord().value() << endl;
46  cout << " Obj: " << t6.outDB().getVariable("z").findRecord().level() << endl;
47 }
48 
50 string getModelText()
51 {
52  return "Sets \n"
53  " i canning plants / seattle, san-diego / \n"
54  " j markets / new-york, chicago, topeka / ; \n"
55  " \n"
56  "Parameters \n"
57  " \n"
58  " a(i) capacity of plant i in cases \n"
59  " / seattle 350 \n"
60  " san-diego 600 / \n"
61  " \n"
62  " b(j) demand at market j in cases \n"
63  " / new-york 325 \n"
64  " chicago 300 \n"
65  " topeka 275 / ; \n"
66  " \n"
67  "Table d(i, j) distance in thousands of miles \n"
68  " new-york chicago topeka \n"
69  " seattle 2.5 1.7 1.8 \n"
70  " san-diego 2.5 1.8 1.4; \n"
71  " \n"
72  "Scalar f freight in dollars per case per thousand miles / 90 / ; \n"
73  "Scalar bmult demand multiplier / 1 / ; \n"
74  " \n"
75  "Parameter c(i, j) transport cost in thousands of dollars per case; \n"
76  " \n"
77  "c(i, j) = f * d(i, j) / 1000; \n"
78  " \n"
79  "Variables \n"
80  " x(i, j) shipment quantities in cases \n"
81  " z total transportation costs in thousands of dollars; \n"
82  " \n"
83  "Positive Variable x; \n"
84  " \n"
85  "Equations \n"
86  " cost define objective function \n"
87  " supply(i) observe supply limit at plant i \n"
88  " demand(j) satisfy demand at market j; \n"
89  " \n"
90  "cost .. z =e= sum((i, j), c(i, j)*x(i, j)); \n"
91  " \n"
92  "supply(i) .. sum(j, x(i, j)) =l= a(i); \n"
93  " \n"
94  "demand(j) .. sum(i, x(i, j)) =g= bmult*b(j); \n"
95  " \n"
96  "Model transport / all / ; \n"
97  "Scalar ms 'model status', ss 'solve status' \n";
98 }
99 
100 
106 int main(int argc, char* argv[])
107 {
108  cout << "---------- Transport 6 --------------" << endl;
109 
110  try {
111  GAMSWorkspaceInfo wsInfo;
112  if (argc > 1)
113  wsInfo.setSystemDirectory(argv[1]);
114  GAMSWorkspace ws(wsInfo);
115  GAMSCheckpoint cp = ws.addCheckpoint();
116 
117  // initialize a GAMSCheckpoint by running a GAMSJob
118  ws.addJobFromString(getModelText()).run(cp);
119 
120  vector<double> bmultlist = { 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3 };
121 
122  // run multiple parallel jobs using the created GAMSCheckpoint
123  mutex ioMutex;
124  vector<thread> v;
125  for(double b : bmultlist)
126  v.emplace_back([&ws, cp, &ioMutex, b]{runScenario(&ws, cp, &ioMutex, b);});
127  for (auto& t : v)
128  t.join();
129 
130  } catch (GAMSException &ex) {
131  cout << "GAMSException occured: " << ex.what() << endl;
132  } catch (exception &ex) {
133  cout << ex.what() << endl;
134  }
135 
136  return 0;
137 }
GAMSJob addJobFromString(const std::string &gamsSource, const std::string &jobName="")
void setSystemDirectory(std::string systemDir)
void runScenario(GAMSWorkspace *ws, const GAMSCheckpoint &cp, mutex *ioMutex, double b)
Run the job with a different scenario.
Definition: transport6.cpp:36
string getModelText()
Get model as string.
Definition: transport6.cpp:50