Just to make sure, I want to ask, if the option EIGEN_YES_I_KNOW_SPARSE_MODULE_IS_NOT_STABLE_YET is documented somewhere.

My question is, if it means, that

1. The code is not stable and can contain bugs
or
2. The code is considered stable, but the API will change in the future.

Or differently: Is there Sparse Code, that I can use in production code?

Thanks,
Johannes

Which version of Eigen do you use? There have been some API changes to the Sparse module lately, e.g. DynamicSparseMatrix has been deprecated. But the good news is that for Eigen 3.1 the Sparse module will move to stable! On the mailinglist Gael wrote that he plans with the first week of February for the release, so it's not that far. An alpha has been released already. If I were you, I'd follow trunk if you start with Sparse just now.

http://eigen.tuxfamily.org/index.php?ti ... 1.0-alpha1

Ok thanks for that insight.

But still, can someone answer: What does EIGEN_YES_I_KNOW_SPARSE_MODULE_IS_NOT_STABLE_YET mean?

1. The code is not stable and can contain bugs
or
2. The code is considered stable, but the API will change in the future.

It was mostly a warning about API stability. I recommend you to directly starts with the 3.1 alpha1 release which contain a saner API base, and a more up-to-date documentation.