// simplified version:
main
{
var init = 1000;
var upto = 0;

thisOplModel.generate();
thisOplModel.ctSpeciesSaved.LB=init;
writeln("Solve "+thisOplModel.ctSpeciesSaved.LB);
cplex.solve();

var filename = "c:/Temp/mipstart"+init+".mst";
cplex.writeMIPStarts(filename, 0, 1); // works with 20.1 not with 12.5
thisOplModel.postProcess();

var newSaved = init-1; // new constraint
while (newSaved > upto){
   thisOplModel.ctSpeciesSaved.LB = newSaved;
   cplex.readMIPStarts(filename);
   writeln("Solve"+newSaved);
   cplex.solve();
   cplex.writeMIPStarts(filename, 0, 1); // writing
   writeln("Write CSV file");
   thisOplModel.postProcess();
   newSaved= newSaved - 1;
}
}

***ERROR[SCRIPT_002] at 149:0 warmstart.mod: Scripting runtime error: unknown property 'writeMIPStarts'.

// simplified version:
main
{
var init = 1000;
var upto = 0;

thisOplModel.generate();
thisOplModel.ctSpeciesSaved.LB=init;
writeln("Solve "+thisOplModel.ctSpeciesSaved.LB);
cplex.solve();

var filename = "c:/Temp/mipstart"+init+".mst";
cplex.writeMIPStarts(filename, 0, 1); // works with 20.1 not with 12.5
thisOplModel.postProcess();

var newSaved = init-1; // new constraint
while (newSaved > upto){
   thisOplModel.ctSpeciesSaved.LB = newSaved;
   cplex.readMIPStarts(filename);
   writeln("Solve"+newSaved);
   cplex.solve();
   cplex.writeMIPStarts(filename, 0, 1); // writing
   writeln("Write CSV file");
   thisOplModel.postProcess();
   newSaved= newSaved - 1;
}
}

***ERROR[SCRIPT_002] at 149:0 warmstart.mod: Scripting runtime error: unknown property 'writeMIPStarts'.

Thanks Alex. This is very useful. Unfortunately I am stuck with 12.5 on the remote hpc.

Looking at my code - I believe I actually don't need the write/read MIPstart if I iteratively change a lowerbound and call cplex.solve() at each iteration. As I am not generating a new model. It seems that cplex keeps the solution from the previous problem as MIP start. Is it correct?

main
{
var init = 682; // start with this ctSpeciesSaved.LB=init;
var upto = 400; // iterate until

thisOplModel.generate();
thisOplModel.ctSpeciesSaved.LB=init; // first LB is init

writeln("Solve "+thisOplModel.ctSpeciesSaved.LB);
cplex.solve();
var curr = cplex.getObjValue();
var upcost = thisOplModel.budget; //new upperbound constraint for next iteration
writeln();
writeln("OBJECTIVE: ",curr);
thisOplModel.postProcess(); // write and process solution in csv file.

var newSaved = init-1; // new target

while (newSaved > upto){
   thisOplModel.ctSpeciesSaved.LB = newSaved; // update LB constraint
   thisOplModel.ctCost.UB = upcost; // update UB constraint
   writeln("Solve"+newSaved);
   cplex.solve(); // solve
   curr = cplex.getObjValue();
   writeln();
   writeln("OBJECTIVE: ",curr);
   upcost = thisOplModel.budget; // update upcost
   writeln("Write CSV file");
   thisOplModel.postProcess();
   newSaved= newSaved - 1; // update newSaved
}
}

Execution on CPLEX 12.5

<<< setup

Solve 682
Tried aggregator 1 time.
MIP Presolve eliminated 1156 rows and 920538 columns.
MIP Presolve added 4499 rows and 4499 columns.
MIP Presolve modified 4024 coefficients.
Reduced MIP has 4638 rows, 48278 columns, and 109559 nonzeros.
Reduced MIP has 31984 binaries, 16294 generals, 0 SOSs, and 0 indicators.
Presolve time = 5.83 sec. (869.66 ticks)
Probing time = 0.05 sec. (7.17 ticks)
Clique table members: 112.
MIP emphasis: optimality.
MIP search method: dynamic search.
Parallel mode: deterministic, using up to 16 threads.
Root relaxation solution time = 1.30 sec. (48.69 ticks)

Nodes Cuts/
Node Left Objective IInf Best Integer Best Bound ItCnt Gap

0 0 6.44747e+09 166 6.44747e+09 211
0 0 6.44747e+09 293 Cuts: 162 517
0 0 6.44747e+09 371 Cuts: 136 775
* 0+ 0 6.44791e+09 6.44747e+09 775 0.01%

Cover cuts applied: 5
Flow cuts applied: 3
Mixed integer rounding cuts applied: 173
Zero-half cuts applied: 30
Gomory fractional cuts applied: 46

Root node processing (before b&c):
Real time = 9.53 sec. (2688.02 ticks)
Parallel b&c, 16 threads:
Real time = 0.00 sec. (0.00 ticks)
Sync time (average) = 0.00 sec.
Wait time (average) = 0.00 sec.
------------
Total (root+branch&cut) = 9.53 sec. (2688.02 ticks)

OBJECTIVE: 6447907838.182847

Solve681
2 of 2 MIP starts provided solutions.
MIP start 'm2' defined initial solution with objective 6.4479e+09.
Tried aggregator 2 times.
MIP Presolve eliminated 0 rows and 640765 columns.
MIP Presolve added 80 rows and 80 columns.
MIP Presolve modified 3673 coefficients.
Aggregator did 39 substitutions.
Reduced MIP has 1336 rows, 323593 columns, and 2236411 nonzeros.
Reduced MIP has 254541 binaries, 69052 generals, 0 SOSs, and 0 indicators.
Presolve time = 15.83 sec. (3207.09 ticks)
....

// simplified version:
main
{
var init = 1000;
var upto = 0;

thisOplModel.generate();
thisOplModel.ctSpeciesSaved.LB=init;
writeln("Solve "+thisOplModel.ctSpeciesSaved.LB);
cplex.solve();

var filename = "c:/Temp/mipstart"+init+".mst";
cplex.writeMIPStarts(filename, 0, 1); // works with 20.1 not with 12.5
thisOplModel.postProcess();

var newSaved = init-1; // new constraint
while (newSaved > upto){
   thisOplModel.ctSpeciesSaved.LB = newSaved;
   cplex.readMIPStarts(filename);
   writeln("Solve"+newSaved);
   cplex.solve();
   cplex.writeMIPStarts(filename, 0, 1); // writing
   writeln("Write CSV file");
   thisOplModel.postProcess();
   newSaved= newSaved - 1;
}
}

***ERROR[SCRIPT_002] at 149:0 warmstart.mod: Scripting runtime error: unknown property 'writeMIPStarts'.