# Left sub/superscript in exponents

I have a small problem with left sub- and superscripts. In my work, I have two regularly occurring indices, that should be distinct from one another. As I have to use exponents of some of these indicated symbols, I can't use right superscripts. If I use left superscripts (with the \prescript command from mathtools), the whole thing looks okay-ish, as left superscripts always do.

But the problem comes, when I have to use one of these symbols as an exponent, see the MWE below

\usepackage{mathtools}
\newcommand{\pre}[1]{\prescript{#1}{}}
\begin{document}
${\bf x} = \begin{bmatrix}\prescript{1}{}x, \prescript{2}{}x, \dotsc \prescript{d}{}x\end{bmatrix}$\mathbb{R}^{\pre{1}n \times \cdots \times \pre{d}n}\pre{j}A \in \mathbb{R}^{\pre{j-1}r \times \pre{j}n \times \pre{j}r}\$
\end{document}


While it looks okay in the first example, the second looks worse and especially the third is very confusing...

Is there anything I can do?

• Hi and again welcome to TeX.SE! The {\bf x} is old syntax. You colud to replace it, for example, with \mathbf{x}. After I wanted to ask you kindly if you could enter the complete code from \documentclass. – Sebastiano Oct 24 '18 at 14:05
• I changed every \bf with \mathbf. What do you mean by \documentclass? I forgot the \end{document} (added that in) – Laray Oct 24 '18 at 14:21
• @Laray Excuse me for my bad English. Starting to \documentclass with others packages that you have loaded. – Sebastiano Oct 24 '18 at 14:29
• @campa, I added screenshots of the output now – Laray Oct 24 '18 at 14:29
• I would say this only demonstrates prescripts are bad typographically, particulary if they are typeset upright (a digit) and with an italic variable (a letter). Also the positioning can't be same for a slanted capital A, a slanted x or an upright R. – user4686 Oct 24 '18 at 15:54