libtexprintf & utftex

The utftex program and underlying libtexprintf library provide tools to pretty print math in mono-space fonts, using a tex-like syntax. It produces UTF-8 encoded text. The program was inspired by asciiTeX, and the improved asciiTeX fork. However, utftex supports much more TeX syntax and contains extensive Unicode tables to map latex commands to Unicode symbols. Use libtexprintf/utftex to unlock the math capabilities of Unicode in mono-space text applications.

Note that how the equations look depends strongly on the font you use. Naturally, one needs a monospace font with good Unicode support for the symbols you use. A good monospace font for math is, for example,
JuliaMono.

libtexprintf

The core library to pretty print math in mono-space font. Use it to enable your c or c++ code to print out formatted math. The calls are modeled after the printf family to produce formatted output.

utftex

The utftex program uses libtexprinf to implement a command-line utility to format math. For example:

> utftex '\frac{\alpha}{\beta+x}'

gives

 α   
───  
β+x

The texprintf library provides a fairly full featured tex-like syntax with arrays, brackets, many symbols, and even font style (note that texprintf outputs UTF-8 and as such cannot change the fonts. However, Unicode does provide several font-styles like mathematical calligraphic style, or italic). For example:

> utftex -F mathnormal '\frac{1}{a+x}'

gives

 1
───
𝑎+𝑥

It also supports some diacritical combining marks, to do things like

utftex '\vec x'

to get

x⃗.

A bit more elaborate example is this small table of Laplace transforms:

> utftex '\begin{array}{|l|l|}  
\hline  
f(t) & \mathscr{L}[f(t)]=F(s) \\\hline  
1 & \frac{1}{s} \\\hline  
e^{at}f(t) & F(s-a) \\\hline  
\delta\left(t\right) & 1 \\\hline  
\delta\left(t-t_0\right) & e^{-st_0} \\\hline  
\int_0^t f(x)g(t-x)dx & F(s)G(s)\hline  
\end{array}'  

┌────────────────┬──────────────┐ 
│f(t)            │ 𝓛[f(t)]=F(s) │  
├────────────────┼──────────────┤  
│                │ 1            │  
│1               │ ─            │  
│                │ s            │  
├────────────────┼──────────────┤  
│ at             │              │  
│e  f(t)         │ F(s-a)       │  
├────────────────┼──────────────┤  
│δ(t)            │ 1            │  
├────────────────┼──────────────┤  
│                │  -st         │  
│                │     0        │  
│δ⎛t-t ⎞         │ e            │  
│ ⎝   0⎠         │              │  
├────────────────┼──────────────┤  
│ t              │              │  
│⌠               │              │  
│⎮  f(x)g(t-x)dx │ F(s)G(s)     │  
│⌡               │              │  
│ 0              │              │  
└────────────────┴──────────────┘

Note that if the table borders do not properly align you are not viewing the table in monospace fonts.

utfstringinfo

Utility to analyze UTF-8 strings. The utfstringinfo program reads arguments or, if no arguments are provided, stdin and for every single character it finds it shows the UTF-8 byte sequence, the Unicode code-point and, if applicable, the utftex command that can be used to generate the symbol.

Software using libtexprintf/utftex

Several projects use libtexprintf or utftex. Some projects that I am aware of are (in arbitrary order):

LibTeXPrintf: a wrapper around libtexprintf to use the library directly from the julia programming language
kramdown-rfc (a backend for kramdown) uses utftex to export latex equations to plain text
utftex-gui, a simple graphical user interface to utftex (much like the gui that came with asciiTeX)

Questions One Might Ask (QOMA)

Why is my equation all misaligned?
- Make sure you are using mono-space fonts.
I am using mono-space fonts, why are my equations still poorly aligned?
- Most fonts do not support all Unicode characters. Your program may use some variable-width fallback fonts.
Why are some symbols are not displayed (properly)?
- Most fonts do not support all Unicode characters. Perhaps your font engine just gave up? This also often happens when using combining diacritical marks. Find the right set of font engine and fonts to use.
Can you recommend a good mono-space symbol font?
- Best is if the monospace font you use supports lots of symbols by itself. There are various fonts that support a great deal of Unicode. See for example this discussion. As mentioned before I recommend JuliaMono.
- Make your own out of your favorite (variable-space) fonts! The great "monospacifier" will do that for you. Get it at https://github.com/cpitclaudel/monospacifier
How do I specify the fallback fonts in <insert some program/system>?
- This will depend on your system and/or program you are using. If your system uses fontconfig you may try that to set up an appropriate mono-space fallback font.
How do I specify the fallback fonts in with fontconfig?
- Let us assume you use some mono-space font called "MONO" and we have some symbol mono-space fallback font for it "SYMBOLMONO". Here are the steps:
  1. Install all fonts (e.g. copy font files to ~/.local/share/fonts and run "fc-cache -f -v")
  2. Then create a fontconfig file in ~/.config/fontconfig/fonts.conf It could look something like (replace the font names with the appropriate values):

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
 <alias>
   <family>monospace</family>
   <prefer>
     <family>MONO</family>
     <family>SYMBOLMONO</family>
   </prefer>
 </alias>
</fontconfig>

bartp5 / libtexprintf