Using GDB with Eigen C++ library

You have to install a gdb extension that you can find in eigen/debug/gdb/.

The comment at the beginning of the file explains how to install it.

One trick you can use is the .data() member, it gives you a pointer to the raw array that contains the data. With that you can print it in GDB like so:

print *X.data()@Length_X

where X is the eigen variable and Length_X is the product of its rows and columns.