Hello, fellow applied mathematicians and computer scientists, hello also to all the brave physicists who use the [arXiv](http://www.arxiv.org/). Did you know that you can [publish source code and other ancillary files on the arXiv](http://arxiv.org/help/ancillary_files), along with your preprint? If you didn't, this must be great news for you. However, if you ever tried to actually do this, you *might* have been just as confused as me. It's actually quite likely that you were, because as soon as this blogpost has vanished from the front page, I am pretty sure that a google search is what led you here. > Ancillary files are included with an arXiv submission by placing them in a directory anc at the root of the submission package. If you are a novice to uploading files to the arXiv, like me, this might be confusing. What is the *submission package*? I only ever submitted a single $\KaTeX$ file! Well, let me put it straight for you. - In the directory with your .tex file(s), make a directory called anc. - Place all your source code and stuff in that directory. - Make a zip file containing all your LaTeX sources and the folder anc. - Upload that zip file to the arXiv. Trust me - everything will be fine.