Re: [Groff] \[-+] not available? why?

[Ted Harding]

On 30-Jul-2014 09:23:54 Anton Shterenlikht wrote:
> To me
> .char \[-+] \f[S]\v'.05v'\z+\v'-.3v'\-\v'.3v'\v'-.05v'\f[]
> 
> looks better vertically aligned, but it's just a bikeshed.
> 
> Many thanks for all replies.
> Anton

Well, now that I can finally get round to it, Denis Wilson:
  .char \[-+] \f[S]\v'.1v'\z+\v'-.25v'\-\v'.25v'\v'-.1v'\f[]
Mike Bianchi:
  .char \[-+] \f[S]\z+\v'-.35v'\-\v'.35v'\f[]

have already come up with suggestions similar to what I was
considering (as well as Anton's above).

The main difference, which I strongly recommend, is to use
'm' rather than 'v' as the scale for the vertical motion.
The reason is that 1v is one line-space, which can be set
independently of the current point-size, while 'm' is, in
effect, the point size, so that the result will scale as
the point-size changes.

What I had devised (and again some tweaking of the motions
may be desirable -- it might look better to shift it down
a bit) is:

  .char \[-+] \Z'\fS+\fP'\v'-0.370m'\fS\[mi]\f[]\v'0.370m'

Then, in plain text,

  \[-+] \[+-]

will display appropriately. And of course one can also define
"-+" for the 'eqn' environment (where it will feel most at home
anyway):

.EQ
define -+ "\[-+]"
cos ( A +- B ) ~~=~~
cos ( A ) cos ( B ) ~ -+ ~ sin ( A ) sin ( B )
.EN

and, to show how the scaling adapts:

.EQ
a ~+-~ b ~-+~ c ~~~~~ e sup{a~ +-~ b ~-+~ c}
.EN

This little thing has provoked quite some interest!

Best wishes to all,
Ted.

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E-Mail: (Ted Harding) <address@hidden>
Date: 30-Jul-2014  Time: 13:40:52
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