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

[Mike Bianchi]

On Wed, Jul 30, 2014 at 01:40:55PM +0100, Ted Harding wrote:
>       :
> 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!

This is what I like about this group!
There is such depth of knowledge that we all can draw on.

Is it possible to make  .char \[-+] ...  something that is part of the
S font by default?

Otherwise we are likely to revisit this in a year or two.

-- 
 Mike Bianchi