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I know that this issue has been treated in many places, but I have yet to reach something conclusive, hence I am herein seeking your help.

Following the 260.3-1993 - American National Standard Mathematical Signs and Symbols for Use in Physical Sciences and Technology document as well as the Typesetting mathematics for science and technology according to ISO 31/XI guide, I ended up typesetting a certain equation as seen below: enter image description here

by using the code:

\begin{equation}
\begin{split}
W_{m}(kR) &= \mathrm{i}^m \left( \mathrm{j}_m(kR) 
             - \frac{\mathrm{j}_m^{\prime}(kR)} {\mathrm{h}_m^{\prime (2)}(kR)} \mathrm{h}_m^{(2)}(kR)\right) \\
     &= \frac{\mathrm{i}^{m+1}} {(kR)^{2} \mathrm{h}_m^{\prime (2)}(kR)},
\end{split}
\label{eq:WmkR}
\end{equation}

with j_m and h_m being the spherical Bessel and Hankel functions.

HOWEVER, the appearance of the imaginary unit as well as the Bessel family functions seem awkward to me, although they comply with the above referenced guidelines documents. Additionally, looking in acoustics books, in wikipedia and a multitude of other resources, I could not spot something that looks like the equation seen above.

The question is, even if this were the correct way of typesetting those functions, would you opt for the usual (albeit probably wrong) formatting of adopting italics?

EDIT (ADDITION): Just to clarify, I find awkward the use of roman letters for the Bessel family functions. Those functions are typeset in italics EVERYWHERE else I looked up.

Willie Wong
  • 73,139
Christos Oreinos
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  • Ahm... sorry, but what is wrong with the equation above? I don't understand. Are the subindex in italacs the problem?

    I need to check the referencies about mathematical orthotypography you use but, as far as I know and as I understand, is common to compose the equations,at least the literals in italics. Only some operators are composed in romans.

     –  Dec 14 '13 at 22:23
  • I don't know what you find awkward about the above equation: can you put your finger on it? 2. Even though certain LaTeX guides recommend otherwise, my personal preference is to always, always typeset the imaginary unit in italics (and also, because the imaginary unit is nearly omnipresent in my field of research, to consistently avoid using it as an index).
    • – Niel de Beaudrap Dec 14 '13 at 22:23
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    @NieldeBeaudrap The mentioned standard is adamant in requiring the imaginary unit to be typeset upright. If one has to comply to it, there's no choice. – egreg Dec 14 '13 at 22:29
  • @NieldeBeaudrap In my case I prefer it upright (together with e —the number— and π —the number—). But about the bessel functions, I think you could find another appearence (I've never seen them that way). – Manuel Dec 14 '13 at 22:30
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    I'd define macros for \mathrm{i}, \mathrm{h} and \mathrm{j} to begin with. Thus you're sure the formatting is uniform (and you can easily change it). – egreg Dec 14 '13 at 22:30
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    This is not a TeX problem or a typesetting problem but a matter of choosing notations. ISO 31-11 was replaced by ISO 80000-2 in 2009, but there is no change in the principle that mathematical constants, such as as the imaginary unit, are written in roman (upright) style. You can follow the standard, or you can follow the nonstandard practice of italicizing constants. What matters is what the rules of the publication you are writing for say about. Regarding the functions, it seems that the prime should appear the entire function symbol. – Jukka K. Korpela Dec 14 '13 at 23:03
  • As pointed before, the question seems off-topic here, it's not about LaTeX, rather about maths typesetting guidelines. AFAIK, this is on-topic on Math.SE. – yo' Dec 14 '13 at 23:30
  • @tohecz You are right. I apologize for hastily posting here. Is there a way to transfer the topic to the Math.SE. section? – Christos Oreinos Dec 14 '13 at 23:34
  • @egreg: well, he did ask "even if this were the correct way of typesetting those functions, would you opt for the usual (albeit probably wrong) formatting of adopting italics?" Do I take it that typesetting i in italics is an even more egregious mis-step than doing so for the Bessel functions? – Niel de Beaudrap Dec 15 '13 at 18:31
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    FWIW, I can't recall ever reading anything where the Bessel functions are typeset upright, and anything where the imaginary unit is typeset just upright. I have seen many times where the imaginary unit is typeset upright and boldface, like $\mathbf{i}$. In LaTeX I would suggest you define macros for these things in the preamble so that you can change it easily throughout the entire document later on, regardless of what you think of doing now. Your hand may be forced eventually by the house styles of the publisher, if this is a document to be traditionally published. – Willie Wong Dec 16 '13 at 10:05
  • FWIW, I once typeset the differential $dx$ in the integrals upright, $\mathrm{d}x$, because, well DIN said that was the way to do it. I was told in no uncertain terms to let that be - Nobody does it, and it's ugly. The first is an exaggeration, there are people who do it. – Daniel Fischer Dec 16 '13 at 10:07
  • @DanielFischer: in non-collaborative documents I always put upright differentials, because I think it actually looks better (especially with double and triple integrals). I also put the differential in upright for differential forms for consistency. – Willie Wong Dec 16 '13 at 10:13