http://sourceforge.net/projects/wxmaxima/files/wxMaxima/15.04.0/wxmaxima-15.04.0.tar.gz
no file wxmaxima.desktop
upstream's .desktop file was renamed (imo incorectly to wxMaxima.desktop) and has regressed a bunch (no MimeTypes or Categories), so I included a replacement (largely based on what was included in 14.09 instead).
wxMaxima-15.04.0-1.fc22 has been submitted as an update for Fedora 22. https://admin.fedoraproject.org/updates/wxMaxima-15.04.0-1.fc22
Package wxMaxima-15.04.0-1.fc22: * should fix your issue, * was pushed to the Fedora 22 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing wxMaxima-15.04.0-1.fc22' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2015-7478/wxMaxima-15.04.0-1.fc22 then log in and leave karma (feedback).
wxMaxima-15.04.0-1.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.