I remember discussing this once in an issue (I can't find it right now). We decided to use dx with no roman type, which is what is done now. I can't remember what the reason for the decision was, although I do recall that I personally prefer using dx with no roman type, as the roman d to me looks bad and out of place.
I also disagree that only variables should be italics is a hard and fast rule. This is just some people's opinion, which they've stated as a universal rule. But if you look for instance at Wikipedia, at https://en.wikipedia.org/wiki/Integral and https://en.wikipedia.org/wiki/Derivative the d is always typeset in italics (see https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Mathematics#Roman_versus_italic). The rule for this varies between disciplines. Some use a roman d and some don't. I wouldn't be opposed to adding an option for this, although I think that the italics d should remain the default. Aaron Meurer On Tue, May 24, 2016 at 8:16 AM, Ondřej Čertík <[email protected]> wrote: > Hi Björn, > > On Tue, May 24, 2016 at 11:09 AM, Björn Dahlgren <[email protected]> wrote: >> I was recently made aware that only variables should be in italics in >> equations (see e.g. [1], [2], [3]). >> I never really reflected over the distinction, but now it seems obvious. >> Should we make LaTeX output of SymPy follow this? >> >> e.g. change: >> >>>>> x = sympy.Symbol('x') >>>>> print(sympy.latex(sympy.Integral(x, x))) >> >> \int x\, dx >> >> to: >> >> >>>>> x = sympy.Symbol('x') >>>>> print(sympy.latex(sympy.Integral(x, x))) >> >> \int x\, \mathrm{d}x >> >> >> >> what do you think? > > Indeed, I always define > > \def\d{{\rm d}} > > and use as: > > \d x > > (I guess I should rather use the Latex's style \mathrm, as you did, > but that's minor.) > > So I am in fact following this rule, but I didn't realize that the > rule is as simple as "only variables should be in italics", but it > does make sense. > > Regarding "dx", there are two styles in typesetting, and I've seen > lots of textbooks in the U.S. to type "d" in italics. Also some people > prefer that, as Kalevi wrote above. > > As such, I think the solution is to add an option to the printer so > that the user can choose which style he or she prefers. > > Ondrej > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/sympy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CADDwiVCseDMagGt4sGsV1PpecTA2Xx7uyV5dWNeV5nxP_ps6Fw%40mail.gmail.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6%2BtdaBJ-7KOQUsrCFMrh8y6-hgb0D4qTAjd59fH33%3DYAw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
