# Fix a formula with fraction 1/2 in subscript mode

At this time for my book I am writing some formulas for radioactive decay. I'm using actually newtxtext package as a text font and mt2pro as a mathematical character and formula font. In the attached code I use newtxmath so that everyone can compile it regularly keeping in mind that the situation is the same using mt2pro. Precisely I would like to write the fraction 1/2 similar to the image below (green rectangle),

In other words, the backslash should be very close to the number 1 and 2, because as you can see in the formula (2), the expression is not only not visually good.

We appreciate your suggestions and your knowledge to make the visualization of my formulas better (especially the exponent of the formula (2)).

Here my MWE for 2nd image:

\documentclass[12pt,a4paper]{book}
\usepackage{newtxtext,newtxmath}
\usepackage{mathtools}

\begin{document}
$$T_{1/2}=\frac {\ln 2}{\lambda}=\tau \ln 2<\tau$$

$$N(t)=N_0e^{-\frac{t\ln 2}{T_{1/2}}}=N_0e^{\ln 2^{-\frac t{T_{1/2}}}}=N_0{2}^{-\frac{t}{T_{1/2}}}$$

\end{document}


The digit 1 is much thinner than the other digits. Most fonts, however, define it with a bounding box equal to the ones for the other digits, for the sake of alignment in tables.

You can solve the special case by defining a suitable command:

\documentclass{article}
\usepackage{newtxtext,newtxmath}

\newcommand{\one}{\mspace{-1mu}1\mspace{-1.5mu}}

\begin{document}

$$T_{\one/2}=\frac {\ln 2}{\lambda}=\tau \ln 2<\tau$$

$$N(t)=N_0e^{-\frac{t\ln 2}{T_{\one/2}}}= N_0e^{\ln 2^{-\frac t{T_{\one/2}}}}=N_0{2}^{-\frac{t}{T_{\one/2}}}$$

\end{document}


I wouldn't touch the slash.

I would also omit the step with the fraction at second level superscript: it is unreadable and actually an easy application of logarithms. A short explanation after the equation is more than sufficient.

\documentclass[12pt,a4paper]{book}
\usepackage{newtxtext,newtxmath}
\usepackage{mathtools}
\usepackage{nicefrac}

\begin{document}
$$T_{\nicefrac{1}{2}}=\frac {\ln 2}{\lambda}=\tau \ln 2<\tau$$

$$N(t)=N_0e^{-\frac{t\ln 2}{T_{\nicefrac{1}{2}}}}=N_0e^{\ln 2^{-\frac t{T_{\nicefrac{1}{2}}}}}=N_0{2}^{-\frac{t}{T_{\nicefrac{1}{2}}}}$$

\end{document}


A little bit late to the party, but better late than never, right?

Since you set the tag mtpro in your query, I think it's ok to recommend that you use mtpro2 (possibly its 'lite' subset) rather than newtxmath as the main math font package. mtpro2 employs optical sizing for first- and second-order subscripts and superscripts; as a result, "thin" glyphs such as 1 don't appear nearly as skinny as those of newtxmath do.

Second, I'd create a macro called, say, \teeonehalf, and define it as follows:

\newcommand\teeonehalf{T_{\mkern-2mu 1\mkern-1.5mu/2}}


By "tucking in" the term 1/2 a bit more below the T character, and by reducing the distance between 1 and /, the 1 character starts to look a bit less skinny.

Last but not least, I'd also like to recommend that you use \exp and inline math notation wherever possible, and thus replace, say, N_0e^{\ln 2^{-\frac t{T_{1/2}}}} with N_0\exp\bigl(\ln 2^{-t/\teeonehalf}\bigr). I think the legibility of the equation is much enhanced by these typographic devices.

\documentclass[12pt,a4paper]{book}
\usepackage{newtxtext}
\usepackage[lite]{mtpro2}
%\usepackage{newtxmath}
\newcommand\teeonehalf{T_{\mkern-2mu 1\mkern-1.5mu/2}}
\begin{document}

$$\teeonehalf= \ln 2/\lambda=\tau \ln 2<\tau$$
$$N(t)=N_0\exp(-t\ln 2/\teeonehalf) =N_0\exp\bigl(\ln 2^{-t/\teeonehalf}\bigr) =N_0\, 2^{-t/\teeonehalf}$$
\end{document}

• It was actually a surprise that I voted positively for the elegance of the code and especially for the explanation. Thank you so much for your kindness. Aug 17, 2020 at 11:51