# If I end a sentence with Ph.~D. how do I tell LaTeX that this IS a sentence end

So, LaTeX automatically knows that "E. Xample" is a name and doesn't add a full sentence ending space to the end of it, right? But if I'm writing Ph. D. I want to put in a marker, so it knows that Ph. isn't the end of a sentence. Ph.~D. or Ph.\ D. depending on if I want it to be able to line break in the middle or not. But what do I do if I'm ending a sentence with Ph. D.? For example: "over the course of my Ph.\ D."

MWE:

\documentclass[]{article}
\begin{document}
\noindent \textit{This space feels wrong as there is too much space between the Ph.\ and D., then not enough after the D:}

\ldots scientific equipment over the course of my Ph.~D.
In addition to gathering all my own data on the X-ray diffractometer\ldots

\vspace{\baselineskip}
\noindent \textit{Now there is WAY to much space between sentences! I thought quad was the normal space between sentences. }

\ldots scientific equipment over the course of my Ph.~D.\quad
In addition to gathering all my own data on the X-ray diffractometer\ldots
\end{document}


• Covered by this question: What is the proper use of \@ (i.e., backslash-at)? Mar 17, 2021 at 20:10
• As a note, I usually see "Ph.D." with no space at all. Mar 18, 2021 at 23:10
• Seconding @chrylis-cautiouslyoptimistic-'s point, the British academic postnominal convention doesn't involve spaces (full stops/periods for the abbreviation also optional). PhD, MPhil, BA, MMathPhil, MBA etc. Medical postnominals sometimes differ because British medical students typical get two degrees (e.g. BM BCh for 'bachelor of medicine, bachelor of surgery' in Latin). Mar 18, 2021 at 23:40
• In North American with periods seems to be standard, but there doesn't seem to be a consensus of with or without spaces, with having spaces being more formal and not having them more standard. Mar 19, 2021 at 22:44

You add \@ before the period.

\quad is a huge space. It's traditionally one em, the amount of space equal to the current type size although if I recall correctly, the cmbx* defines an em to be wider.

• Thank you. This helps clarify my muddled brain on the issue of \  vs \@ usage. Mar 17, 2021 at 19:03
• @StevenB.Segletes My (sloppy) way to remember how to use it is to think of \@ as of an invisible lowercase letter. Mar 17, 2021 at 19:51
• @campa that's exactly how I taught it when I taught LaTeX classes in the 90s. Mar 17, 2021 at 20:51
• @campa As \@ is defined to expand to \spacefactor with the value of a lowercase letter, that is pretty much precisely what it is.
– ljrk
Mar 18, 2021 at 11:54

Another way is given in The TeXbook, Exercise 12.6.

What can you do to make TeX recognize the ends of sentences that do end with uppercase letters (e.g., ‘... launched by NASA.’ or ‘Did I?’ or ‘... see Appendix A.’)?

There are several ways; perhaps the easiest are to type ‘\hbox{NASA}.’ or ‘NASA\null.’ (The \null macro is an abbreviation for ‘\hbox{}’.)

So Ph.~D\null. works, actually quite the same way as Ph.~D\@. does, resetting the space factor to 1000. I suppose the latter is more LaTeX'y just like anything that contains the character @.