Small and incomplete yet quite useful algebra system for linear operators.
You might want to have a look at LinearMaps.jl and
LinearMapsAA.jl which are similar and more complete in several regards,
but didn't suit my purposes at the time.
If you use my package, please leave a star! Your appreciation is my motivation. If my code helps you with your research, please cite it as follows:
@misc{Horger2022,
title = {Julia package for basic algebra of linear operators expressed by functions (LinearOperators.jl)},
url = {https://github.com/felixhorger/LinearOperators.jl},
author = {Felix Horger},
year = {2022}
}