NetSysFire [1] filed a deletion request for spectral-matrix [2]: Abandoned by upstream, no commits in 5 years. Has broken dependencies (libqtolm is missing). Apparently hasnt been buildable in 4 years according to comments. Even if it would still build, it would fall over because matrix changed a lot in 5 years.
[1] https://aur.archlinux.org/account/NetSysFire/ [2] https://aur.archlinux.org/pkgbase/spectral-matrix/
