Bit arithmetic on Unicode characters?

[Hans Åberg]

> On 7 Oct 2016, at 18:06, Doug Ewell <doug at ewellic.org> wrote:

> I can't find anything in the UCD that distinguishes one "font variant"
> from another (UnicodeData.txt shown as an example):
> 
> 1D400;MATHEMATICAL BOLD CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;
> 1D434;MATHEMATICAL ITALIC CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;
> 1D468;MATHEMATICAL BOLD ITALIC CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;
> 1D49C;MATHEMATICAL SCRIPT CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;
> 1D4D0;MATHEMATICAL BOLD SCRIPT CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;
> 1D504;MATHEMATICAL FRAKTUR CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;
> 1D538;MATHEMATICAL DOUBLE-STRUCK CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;
> 1D56C;MATHEMATICAL BOLD FRAKTUR CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;
> 1D5A0;MATHEMATICAL SANS-SERIF CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;
> 1D5D4;MATHEMATICAL SANS-SERIF BOLD CAPITAL A;Lu;0;L;<font>
> 0041;;;;N;;;;;
> 1D608;MATHEMATICAL SANS-SERIF ITALIC CAPITAL A;Lu;0;L;<font>
> 0041;;;;N;;;;;
> 1D63C;MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL A;Lu;0;L;<font>
> 0041;;;;N;;;;;
> 1D670;MATHEMATICAL MONOSPACE CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;
> 
> And that's probably as it should be, because UTC never intended MAS to
> be readily transformed to and from "plain" characters. They're supposed
> to be used for mathematical expressions in which styled letters have
> special meaning.

I use them for input text files, and it is not particularly difficult. An efficient method is to use text substitutions, as available on MacOS. The resulting file is UTF-8 with the correct character, and typesetting systems like LuaTeX with ConTeXt or LaTeX/unicode-math translates it into a PDF. It is usually easy to immediately spot if a math style is wrong. Using it in the input makes one more aware of new styles that in the past was not available.