Trying to install and use Eigen matrix algebra package

It appears to me that devpkg-eigen has nothing to do with the Eigen3 C++ package. I downloaded it, tried a test program, and obtained a fatal error for trying to include Eigen/Dense. Neither “find” nor “which” produce an “eigen” or an “Eigen” after downloading devpkg-eigen. I have not found clues to a package for Eigen3. The swupd package search facility refers me to devpkg-eigen, but I now am skeptical.

Any problem with installing the Eigen3 package directly?

The bundle you’ve downloaded is for and includes Eigen/Dense in its headers.

which isn’t going to find eigen as it contains no binaries to find as it’s headers and templates. The eigen files should be installed to /usr/include/eigen3

Depending on what directory you ran find in (and whether you specified a directory to search), it will only search from your current path. Opening up a terminal and typing find eigen will only search your home directory for it (and won’t find it). find / eigen should find it though.

One problem I see with devpkg-eigen is that it doesn’t include the development packages for openblas, suitesparse etc which the header files may refer to and hence be unable to import them. I suggest you include the full error seen so we can tell if this is the case.

Here is the “find” output from /

find -name eigen

find: ‘./run/user/1000/gvfs’: Permission denied

A confession here. I probably should have run "find" as su.

eigen3 indeed is in /usr/include, and compilation works when that

path is specified. Searching on
eigen3 produces results:
find -name eigen3
./usr/include/eigen3 <---------------

If I may, your comment about the development packages for openblas,

suitesparse, etc. raises one issue for me. I have been given to
understand that the libraries in the bundles are not siloed in their
bundles, but are shared.

I appreciate your having helped me get my head around this.