Starred formulas

Starred Formula
Sometimes, especially in presentations, I want to tag a formula using a star rather than using a formula number. In LaTeX, this is easy. Just use \tag{...}:

\begin{equation}
a^2 + b^2 = c^2\tag{\ensuremath{\star}}
\end{equation}

However, ConTeXt currently does not have any command that is equivalent to \tag. I used to go through a log of hoops to get starred formulas. Today, I just realized the proper way to get them.

Instead of thinking in a ad-hoc manner like \tag{...} think systematically. What will be the tag for the next formula. ★★ . And next. ★★★. And then? Using a string of stars soon becomes unbearable, so we have to use some other symbol. So, essentially, starred formulas are another way to number formulas. So, what I need is to specify how to convert numbers to symbols. Ah! ConTeXt has an option for that. I can get starred formulas by
using (in MkIV)

\defineformula[star][numberconversion=set 1]

or using (in MkII)

\defineformula[star][conversion=set 1]

This defines a \startstarformula ... \stopstarformula that is similar to \startformula ... \stopformula but uses set 1 conversion. set 1 is one of the predefined conversion functions in ConTeXt which is equal to {★ , ★★, ★★★, †, ††, †††,, *, **, ***}. Each symbol in the set is used cyclically as the formula “number”. Other predefined symbol conversions are

  • set 0 {•, – , ★, △, ○, medcircle, ◯, □}
  • set 2 {*, †, ‡, **, ††, ‡‡, ***, †††, ‡‡‡, ****, ††††, ‡‡‡‡}
  • set 3 {★ , ★★, ★★★, ‡, ‡‡, ‡‡‡, ¶, ¶¶, ¶¶¶, §, §§, §§§, *, **, ***}

If you want a different set of symbols, you can define your own conversion using

\defineconversion[myset][list of comma separated symbols]
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