Re: [Groff] Integral signs

[Joerg van den Hoff]

On Wed, Feb 28, 2007 at 01:42:38PM +1100, Miklos Somogyi wrote:
> Dear Folks,
> 
> I need some integral signs with circles/ellipses around them (e.g. for 
> control volumes).
> I've experimented a lot but only got something that is just acceptable 
> in print,
> but downright ughhly in Preview and Acrobat.
> 
> How would you stretch the circle of the double- and triple integrals?
> I've tried \(ci  instead of `o' but it looks very thin compared to 
> thick int signs.
> What can you suggest (espec something scalable)?
> 
> Thanks,
> 
> Miklos
> 
> 
> 
> 

I'm sure there is some low level way to do this, otherwise `pic' won't work
anyway, but maybe you can use some ugly construct like:

.EQ
delim $$
.EN
.PS
.ps  24
ps = 24
eh = ps / 140
ew = 4 * eh
bw = 10 * eh 
ellipse height eh width ew "$int int int$"
box invis width bw with .w at last ellipse.e "$f(x, y, z) dV$" 
.PE

(and shoving this into a macro might even preserve readability of the document
source ...)

this would work only for display equations, not for inline equations. I'm not
sure if one can use troff registers within `pic'. if so, one could avoid to
dublicate the point size definition (needed for the empirical "scalability"),
but `ps = \n[.s]' does not work, it seems.

HTH

joerg