the project crash

[aya]

I have built two polygons named PG1 and PG2. One is (0,0),(1,0),(1,1),(0,1), the other is (0.25,0.25),(0.75,0.25),(0.75,0.75),(0.25,0.75). At this time the distance returned is 0.25 and closestPoints() returns successfully. However, if I move PG2 out of PG1 and run it aggin. The project crashed in closestPoints(). The package I use is geos-3.1.0rc2. Now I need to find the nearest points of two polygons and the related distance. If there is something wrong in my codes or other solution, please tell me in time. Thanks.

CoordinateSequence *cs;

cout<<PG1->distance(PG2)<<endl; cout<<PG2->distance(PG1)<<endl;

typedef geos::operation::distance::DistanceOp DOP;

DOP *Dis = new DOP(PG1, PG2);

cout<<"in"<<endl; cs=Dis->closestPoints(); cout<<"out"<<endl;