Hi all,

thanks for the great work on Eigen!!

Using it, I stumbled upon the following question:

Assume I have created an Eigen sparse matrix and have called makeCompressed().

Assume further, I am accessing the internal CRS arrays through
outerIndexPtr()
innerIdexPtr()
valuePtr()

I would like to pass the resulting arrays to an external linear algebra solver which may reorder the indizes in the innerIdxPtr() (and the respective valuePtr() arrays. It will stay a valid CRS matrix, but for example the index to the diagonal entry might be reordered to the beginning of each innerIdxPtr() row.

The matrix would remain identical, just the internal CRS ordering might change. Is that allowed? Does Eigen internally expect a certain ordering?

cheers,
Sebastian

Many operations require that the entries are sorted. You can re-order them with a copy to a column-major matrix.