1  int n = 10000;
2  VectorXd x(n), b(n);
3  SparseMatrix<double> A(n,n);
4  /* ... fill A and b ... */
5  BiCGSTAB<SparseMatrix<double> > solver(A);
6  // start from a random solution
7  x = VectorXd::Random(n);
8  solver.setMaxIterations(1);
9  int i = 0;
10  do {
11    x = solver.solveWithGuess(b,x);
12    std::cout << i << " : " << solver.error() << std::endl;
13    ++i;
14  } while (solver.info()!=Success && i<100);