Someone "reinvented" our algorithm, is there anything to do about that?
The place to start, if the authors don't respond, is to contact the editors of the journals that published both papers - or at least the editor of the other - pointing out the issue and giving references. 

Perhaps nothing improper has happened, but you can at least ask for a note/erratum posted with the other paper so that you get more visibility. 

I doubt that you can get more than that, but if you start there, at least, you can get proper recognition. 

Parallel work is pretty common. Not recognizing something similar if it appears in another field seems pretty natural. Maybe something worse, but hard to know. Contacting their editor may get them to contact you, one hopes. 

BTW, the reason for contacting your own editor is that they might also get involved in a solution.