condtwin.gms : CONOPT with two solves in a row

Description

```This model checks if it is possible to run conopt with solvelink 5 two times
in a row, then with cplex, at the end two times with conopt again.

Contributor: Lutz Westermann
```

Small Model of Type : GAMS

Category : GAMS Test library

Main file : condtwin.gms

``````\$Title CONOPT3 with two solves in a row (CONDTWIN,SEQ=366)
\$Ontext

This model checks if it is possible to run conopt with solvelink 5 two times
in a row, then with cplex, at the end two times with conopt again.

Contributor: Lutz Westermann

\$Offtext

Sets
i   canning plants   / seattle, san-diego /
j   markets          / new-york, chicago, topeka / ;

Parameters

a(i)  capacity of plant i in cases
/    seattle     350
san-diego   600  /

b(j)  demand at market j in cases
/    new-york    325
chicago     300
topeka      275  / ;

Table d(i,j)  distance in thousands of miles
new-york       chicago      topeka
seattle          2.5           1.7          1.8
san-diego        2.5           1.8          1.4  ;

Scalar f  freight in dollars per case per thousand miles  /90/ ;

Parameter c(i,j)  transport cost in thousands of dollars per case ;

c(i,j) = f * d(i,j) / 1000 ;

Variables
x(i,j)  shipment quantities in cases
z       total transportation costs in thousands of dollars ;

Positive Variable x ;

Equations
cost        define objective function
supply(i)   observe supply limit at plant i
demand(j)   satisfy demand at market j ;

cost ..        z  =e=  sum((i,j), c(i,j)*x(i,j)) ;

supply(i) ..   sum(j, x(i,j))  =l=  a(i) ;

demand(j) ..   sum(i, x(i,j))  =g=  b(j) ;

Model transport /all/ ;

option lp=%system.nlp%;
option rmip=soplex;

Solve transport using lp minimizing z ;
Solve transport using lp minimizing z ;

Solve transport using rmip minimizing z ;

Solve transport using lp minimizing z ;
Solve transport using lp minimizing z ;
``````
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