Apple - Single application not showing up in Spotlight

Go to System Preferences --> Spotlight --> Privacy. While that's open, go to Finder --> Applications and drag Matlab from Applications into Privacy. Close out System Preferences then reopen it and remove Matlab from the same place.

This will force a reindex for Spotlight. I've seen this work for some people and not for others but it's worth a shot.

In a terminal, enter:

sudo mdutil -E /

I tried the Preferences --> Spotlight --> Privacy suggestion with the /Applications folder but that did not work for me.

Then I tried sudo mdutil -E /Applications in a terminal, and that didn't work either.

It's possible that using the Preferences --> Spotlight --> Privacy suggestion with the entire disk would have worked also, but in any case, I find typing that single command (sudo mdutil -E /) on the command line easier.

This command starts the reindexing process and then quickly exits, so it may take a while after it has run for your application to be accessible via Spotlight. An easy way to see if it's still indexing is to start spotlight (command-space) and type at least 1 character. If it's reindexing, it will say "Indexing" just below the text entry field.

I've never tried it, but running mdimport -d1 /Applications/ in the Terminal might work as well. You can increase the number up to 4 for increasing debugging information, which might tell you why the indexing isn't working. You can find other command line options at mdimport's man page.