# Difference between revisions of "LaTeX area"

Note: Some of the content on this page is based on Max's personal opinion.

We commonly need to create create written articles of various formats and lengths as well as other visual material such as posters or slideshows. Most of the content gets used multiple times, yet the look and feel of the visual medium can vary wildly — ranging from phone screens over books to video projectors. Making the content look good and, ideally, reusing it in other documents involves adapting its style to the respective medium. For this reason, static content is bad.

What we need is a typesetting system that lets us create all the material (text, equations, tables, figures, everything) in one common organic format and transparently adapt its display style to the target medium. This involves reflowing the text according to the page/screen layout while making figures and other content of various information density optimally accessible to the viewer. Such a system is conceivable but presently does not exist. Layout-heavy file formats like Word / PowerPoint / etc. are broken by design and not worth considering for any purpose. Despite (or, more accurately, because of) their layout flexibility, they universally fail at producing sufficient quality for any medium. In principle, one could invent an abstract description language capable of doing everything we need, and such attempts in fact exist (e.g., extending XHTML with MathML, SVG for drawings, JavaScript-based interactive plotting like Bokeh), but the reality of it is that the client support and therefore the resulting quality of all existing document formats varies so wildly that they are effectively useless unless the range of target media is very limited. Ironically, the only format with good cross-platform support and printability is PDF, a format specifically designed to produce the exact same document on any target medium: this idea seemed fine 20 years ago but is the opposite of what is needed today and in the future.

Keeping in mind that technology is likely to evolve and these problems may all be a thing of the past 5 to 10 years from now, we have to be content with the best option available today, which is to use LaTeX for all our content and make a static PDF for each envisioned medium. While at least most computer screens are about the same aspect ratio and size today, the variety of phone screens limits what we can do with a handful of PDFs. It is, however, clear that paper and anything electronic are incompatible in terms of page layout, so a written document cannot be produced with fewer than 2 PDF files, and then screen presentations etc. are yet another matter.

### Page layout

Letting a writer define their own page layout (margins etc.) almost universally leads to a terrible result because few people have a good understanding of typography<ref> As a rule of thumb, the average number of characters per line should not be much greater than 60. With the exception of two-column layouts commonly found in journals, most pieces of scientific writing violate this rule, making it hard to read more than a page or two without getting fatigued. However, two-column layouts, while allowing for an acceptable line width for readability, cause different problems:

• Any mismatch between page geometry and screen/paper geometry is exacerbated: If you have to zoom in to be able to read the font, you will need to scroll back to the beginning of the page to see the second column.
• Some elements (figures, tables, equations) may need to be wider than a single column. While this can be accomplished by making them span across both columns, that makes the zooming issue even worse.
• The lack of empty space on the page makes adding a binding correction impossible, so paper copies of these documents cannot be stapled or put in a folder.

The only way out of this dilemma is to use a single-column layout of reasonable line width and, in the case of A4/Letter paper, leave margins that look unusually large and wasteful to the eyes of most people corrupted by bad typesetting software. Such a layout has always been the default in LaTeX (e.g., documentclass article) for good reasons. The argument about saving paper by putting more text on it is completely irrelevant, and I am saying this as a massive environmentalist.

### Math, numbers, units

The typographical details of mathematical content have a meaning. There is usually exactly one correct way, and anything else is not only wrong but also risks semantic distortion.

• Read the SI brochure if you haven't. There are more binding ISO standards with basically the same content, but their numbers keep changing and some of the contents are not available for free.
• NIST SP 811 elaborates on these standards; also a good read.
• Here are some recommendations for how to do things right in LaTeX. While this document is from 1997, to my knowledge there is still no better universal way to solve the problem with the total differential operator.

My LaTeX recommendations for a correct and non-tedious implementation of all this:

• Exclusively use siunitx for any non-trivial numbers, any units, and any combination thereof. Turn off your brain and use all commands as intended. Read the manual if you haven't (and save it).
• Use mhchem for chemical elements.
• Either \text or \mathrm can be used for roman typeface in math mode (e.g., subscripts that aren't quantities), but they treat spacing differently. Use \text when in doubt.