Do I need to cite Mathematica in my paper? I am in the final stages of writing my first paper, in dynamical systems. The paper is purely theoretical but I use Mathematica for some images and graphical simulations (none of the actual results depend on a computation by Mathematica). The paper will be presented in a conference, where I will show some of these simulations in real time. 

My question is whether I need or should cite Mathematica in my paper somehow.

More generally - had I used, say, Matlab, or an open source python library instead, would I need to cite them?
I would recommend to always cite software that you use in your calculations (no need for LaTeX, obviously). 
A screw driver will always stay a screw driver, but software is a little bit more complex. 

Have you heard of the little bug that may invalidate 15 years of brain research? I think in that case it would be quite nice to know which version of the software you used. 

And in your case: can you really be sure that Mathematica has not a specific bug that you haven't noticed? In Version 10, I noticed that some linear-log plots were messed up and that was fixed in a later version 10.1. It could have easily happened that I had published a wrong graph, and thus I think it is quite important to give detailled information about the software that you use.