By default installed packages are not available from the Octave prompt, but it is possible to control this using the pkg load and pkg unload commands. The functions from a package can be added to the Octave path by typing
pkg load package_name
where package_name is the name of the package to be added to the path.
In much the same way a package can be removed from the Octave path by typing
pkg unload package_name
© 1996–2018 John W. Eaton
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https://octave.org/doc/interpreter/Using-Packages.html