Diagonal Preconditioner's factorize() routine causes seg fault for (square) SparseMatrix of size 128 and greater

Submitted by Patrick

Assigned to Nobody

Link to original bugzilla bug (#485)
Version: 3.1
Operating system: Linux

Description

I've been getting segfaults while attempting to use the ConjugateGradient solver for a sparse system. gdb traces the fault back to the it.value() call near line 83 of in the factorize() method in BasicPreconditioners.h , when attempting to compute a new ConjugateGradient solver. Strangely this seems to happen exactly when the problem size is 128 or greater.

----This works:

int n = 127;
SparseMatrix<double> A(n,n);
// ...
Eigen::ConjugateGradient< SparseMatrix<double> > cg(A);

----This works:

int n = 128;
SparseMatrix<double> A(n,n);
// ...
Eigen::ConjugateGradient< SparseMatrix<double>, Eigen::Lower, Eigen::IdentityPreconditioner > cg(A);

-----This induces a seg fault:

int n = 128;
SparseMatrix<double> A(n,n);
// ...
Eigen::ConjugateGradient< SparseMatrix<double> > cg(A);