boldtensors — Modernized Bold Tensor Notation for LaTeX

Version: 2.2 Date: 2026-05-21 Authors: Werner Fink & Jürgen Bachteler License: GNU General Public License, version 2 (GPLv2)

---

Description

The boldtensors package provides a highly efficient shorthand for typesetting Latin and Greek characters in bold and blackboard-bold layouts. It is specifically designed for the requirements of Theoretical Physics and General Relativity, where a clear visual distinction between geometric tensor objects and their components or scalars is essential.

The package uses active characters (~ and ") to keep the source code clean and readable:

• `$~T$` produces a bold tensor $\boldsymbol{T}$.
• `$"R$` produces a blackboard-bold symbol $\mathbb{R}$.

Key Features:

• Engine Independent: Fully compatible with both classical pdfLaTeX (using NFSS) and modern LuaLaTeX (using unicode-math and OpenType fonts).
• ISO Compliance: Includes the bt-isodiff sub-package for upright differential operators according to ISO 80000-2.
• Accurate Metrics: Correct placement of subscripts, superscripts, and accents (like \hat{~T}) by using native math characters instead of boxes.
• Micro-Typography: Preserves perfect kerning and font-specific metrics.

---

Files in this Distribution

• boldtensors.sty: The main LaTeX package.
• bt-isodiff.sty: Independent package for upright ISO differentials (can be used separately).
• boldtensors.tex: Documentation source and example file.
• boldtensors.pdf: Compiled documentation.
• README.md: This file.

---

Installation

1. Copy boldtensors.sty and bt-isodiff.sty into your local TeX directory (e.g., ~/texmf/tex/latex/boldtensors/).
2. Update your filename database (e.g., run texhash or use your TeX distribution's GUI).
3. In your LaTeX preamble, add:

   \usepackage[nabla,differential]{boldtensors}

Usage

Bold Tensors

Use the tilde ~ inside math mode to make the following character bold:

`$~A + ~B = ~C$`

`~\alpha_{\mu\nu}`

`~\partial_i` (Bold partial derivative)

Blackboard Bold

Use the double quote " for blackboard symbols:

`$"R, "C, "N$`

Differential Operators (ISO)

When the differential option is used, the character d is automatically rendered upright:

`$ds^2 = g_{\alpha\beta} dx^{\alpha} dx^{\beta}$`

History

1995: Original version by Werner Fink and Jürgen Bachteler at the Institute for Theoretical and Applied Physics, University of Stuttgart.

2007: Maintenance update.

2026: Full modernization for LuaLaTeX/OpenType-Math and ISO 80000-2 compliance. Rename isodiff.sty to bt-isodiff.sty

License

Copyright (C) 1995-2026 Werner Fink.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.