you need call initial solve before branchAndBound.<br><br><div style="margin-left:40px"> CbcModel solver(solver1);<br> solver.initialSolve();<br>
solver.branchAndBound();<br><br></div>Att.<br>Ivan<br><br><div class="gmail_quote">On Wed, Sep 19, 2012 at 4:45 AM, 刘峰 <span dir="ltr"><<a href="mailto:liufengaarr@gmail.com" target="_blank">liufengaarr@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Dear Sir:</div><div> My name is LiuFeng, I am a student of Computer Science In Ji Lin University of China. I am learning to use CBC Library to solve some MIP problems. I met a problem,but I don't know how to solve it.</div>
<div> The problem is as follows.</div><div> It is an Integer Programming problem.</div><div> The target function is Min z=x1 + x2 + x3 + x4</div><div> The Constraints are</div><div> 4*x1 + 3*x2 + 2*x3 =2</div>
<div> x2 + 2*x3 + 5*x4 = 2</div><div> xi >= 0 (i=1,2,3,4) all of them have the constraint of integer.</div><div> </div>
<div> The CBC Codes is as follows:</div><div>int _tmain(int argc, _TCHAR* argv[])<br>{</div><div> OsiClpSolverInterface solver1;<br> const int numcols = 4;<br> const int numrows = 2;<br> int nnz = 6;<br>
CoinBigIndex *start = new int[numcols+1];<br> int* index = new int[nnz];<br> double* value = new double[nnz];<br> double *collb = new double[numcols];<br> double *colub = new double[numcols];<br> double *obj = new double[numcols];<br>
double *rowlb = new double[numrows];<br> double *rowub = new double[numrows];<br> //object<br> obj[0] = -1.0; obj[1] = -1.0; obj[2]=-1.0; obj[3]=-1.0;</div><div> // column bounds<br> collb[0] = 0; colub[0] = solver1.getInfinity(); <br>
collb[1] = 0; colub[1] = solver1.getInfinity(); <br> collb[2] = 0; colub[2] = solver1.getInfinity(); <br> collb[3] = 0; colub[3] = solver1.getInfinity(); </div><div> // matrix<br> start[0]=0; index[0] = 0; value[0] = 4.0;<br>
start[1]=1; index[1] = 0; value[4] = 3.0;<br> index[2] = 1; value[5] = 1.0;<br> start[2]=3; index[3] = 0; value[6] = 2.0;<br> index[4] = 1; value[7] = 2.0;<br> start[3]=5; index[5] = 1; value[8] = 5.0;<br> start[4]=6;</div>
<div> // row bounds<br> rowlb[0] = 2.; rowub[0] = 2.;<br> rowlb[1] = 2.; rowub[1] = 2.;<br> solver1.loadProblem(numcols, numrows, start, index, value, collb, colub, obj, rowlb, rowub);<br> solver1.setInteger(0); // Sets x0 to integer<br>
solver1.setInteger(1); // Sets x1 to integer<br> solver1.setInteger(2); // Sets x2 to integer<br> solver1.setInteger(3); // Sets x3 to integer<br> solver1.setObjSense(-1000.0); // Maximise</div><div> CbcModel solver(solver1);<br>
solver.branchAndBound();<br> bool optimal = solver.isProvenOptimal();<br> const double *val = solver.getColSolution();<br> printf("Solution %g %g %g %g\n", val[0], val[1], val[2], val[3]);<br> return 0;</div><div>
}</div><div> </div><div> I can't get the result. Would you please tell me how to solve them?Thank you very much!<br></div>
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