0
$\begingroup$

In my high school and college math classes, I've always seen graphs drawn with either no arrows on the ends of the axes or with arrows on both ends.

A colleague recently argued with me that this was crazy and arrows are always placed on one side of each axis to indicate the positive direction. Like so: enter image description here

Which style is more prevalent?

  • 6
    I think the convention of having the positive directions be right and up are pretty well set, making the arrows pretty unnecessary for anything besides decoration.2011-07-19
  • 0
    I don't put arrowheads, but if I saw them then I would prefer them positive only. Note that on a map, there is often only one, for North.2011-07-19
  • 1
    I have to say that as a mathematician I am continually surprised at the number of questions on this site which are purely about conventions of various kinds (notation, terminology, practices). If it makes anyone feel any better: I give you permission to draw your axes however you want! (Does it make anyone feel any better?)2011-07-19
  • 1
    @Pete I agree completely; when it's a question of "what should I write for this assignment?", it does not matter at all (and if it does, then the teacher/professor probably already specified). When it's a question of "what should I write in this paper?", again it shouldn't matter as long as whatever you use is clear. However, I'm working on the exercise framework for [Khan Academy](http://khanacademy.org), a situation where it is important to use whatever convention will be the most comfortable for students.2011-07-19
  • 1
    @rubergly: What you say in your last comment sounds like better motivation than winning a rather pointless argument with your colleague. Perhaps you should edit that into your question. (Still, it's not clear to me that there will be a definitive answer to questions like this.) You might just want to flip through a stack of math textbooks at approximately the same grade level as your course and see if there's any unanimity to what they do.2011-07-19
  • 0
    @Pete L. Clark: I've decided not to comment on whether your continuing surprise is somewhat naive.2011-07-20

2 Answers 2