Re: Five glyphs: a minor PostScript challenge

[Tadziu Hoffmann]

> > A. \[-+]: The minus-plus.  We should be able to dynamically generate
> >   this from \[+-] by reflecting the latter about a horizontal axis.  If
> >   the glyph is flipped within its bounding box, I guess the result
> >   would need to be vertically shifted to align it on the baseline.
> 
> This needs a lot of work but might get you started.
> 
>   \s+1\fB+\h'-0.55m'\v'-0.30v'\-\v'+0.30v'\fP\s-1

That would be my ansatz as well: simply assemble the glyph
in groff itself.  Note also that some fonts have a weirdly
squished plus-minus sign, which is ugly.  Building it from
a real plus sign and a real minus sign ensures consistency
in the shapes.  Here's my solution for Times + Symbol that
I came up with some time ago:


  .\" eqn
  .\" ----------------------------------------------------------------
  .sp 3c
  .ps 72
  .vs 74
  .fp 1 R Times-Roman
  .fp 2 I Times-Italic
  .fp 3 S Symbol
  .char \(pm \v'-0.11m'\Z'+'\v'0.34m'\-\v'-0.23m'
  .char \(mp \v'-0.23m'\Z'\-'\v'0.34m'+\v'-0.11m'
  .gcolor red
  .EQ
  a +- b
  .EN
  .sp -1
  .gcolor
  .EQ
  define pm % type binary font S \(pm %
  a pm b
  .EN
  .br
  .EQ
  define mp % type binary font S \(mp %
  a mp b
  .EN