libarmadillo4 software package provides streamlined C++ linear algebra library, you can install in your Debian 8 (Jessie) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install libarmadillo4
libarmadillo4 is installed in your system.
Make ensure the libarmadillo4 package were installed using the commands given below,
$ sudo dpkg-query -l | grep libarmadillo4 *
You will get with libarmadillo4 package name, version, architecture and description in a table
| Distro | Debian 8 jessie |
| Section | Libraries |
| Package | libarmadillo4 |
| Version | 1:4.450.2+dfsg-1 |
| Description | streamlined C++ linear algebra library |
| Sub Section | libs |