In a paper with a co-author who contributed one part (say, computer implementation), where should the contributions of the authors be outlined? If I write a paper, and another person provides a computer program that visualizes the idea, where should I mention the roles of the authors? Is the &quot;acknowledgements&quot; section appropriate for this? Or it is considered a bad tone to delineate the contributions of the co-authors?
If the journal wants you to specify which co-authors contributed which parts of the work, then the journal's guidelines for authors will tell you that clearly, and give you instructions for where in the paper to do it.  If the journal's guidelines don't say anything about it, then you don't need to specify which authors did what.