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

[Denis M. Wilson]

On Wed, 30 Jul 2014 13:40:55 +0100 (BST)
(Ted Harding) <address@hidden> wrote:

> 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!
> 

Indeed Ted! But I would make some small adjustments (a) make -+ the
same size as +- (b) lower it as you suggest; to my eye (both next to
+- and in an equation context) the following is nearly what we want:

 .char \[-+] \v'.07m'\Z'\fS+\f[]'\v'-0.368m'\fS\[mi]\f[]\v'0.368m'\v'-.07m'

Following eqnrc I defined it as follows

sdefine -+ %{ type "binary" \[-+] }%

Denis


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