Your test code also works well on my machine.

But my own still does not work. I will see what I can do to
provide you with more useful information.

D.

I think I figured out the remaining problem.

In SparseMatrix.h, line 1084, you can see the definition of "positions":
VectorXi positions(dest.outerSize());

In my data, some numbers in the vector of "positions" are too large
to be represented by integers. So I changed VectorXi to VectorXl (long).
Then the problem went away. Of course we need to define VectorXl first.

D.

ah, thanks for finding this. I only searched for 'int'. Fixed:

https://bitbucket.org/eigen/eigen/commits/3b221f1f7633/
Changeset: 3b221f1f7633
User: ggael
Date: 2014-02-19 21:42:29
Summary: More int versus Index fixes