suspected `eqn' bug.

[joerg van den hoff]

hello,

currently coming back to groff more seriously after quite a long time (so having got somewhat 
"rusty"), I have stumbled today over the following (observed with version 1.22.4 and ms macros):

I tried to use the `eqn' `gfont' command for switching the font used in equations to something 
different from the default I style of the presently selected font family. this works as advertised
*except* when issuing

gfont PI

which fails to do what it should (namely switching to Palatino italics). consider the following 
ms-document demonstrating the issue.

.\"----------------------------------------------------------------------
.nr PS 14
.nr VS \n(PS+4
.ds FAM H
.LP
The following equation should be typeset with Palatino as italic font but it is 
not
since the  eqn command
\*Qgfont PI\*U
does not work correctly.
Since the font is not set correctly, as a fallback it seems the current regular
font (in the present example: Helvetica) is used:
.EQ
gfont PI
E = m cdot c sup 2
.EN
.ds FAM P
.LP
Only when setting the font family to Palatino (as done here) and then using
\*Qgfont\~I\*U
(or omitting the gfont command completely since using
.B I
from the current font family is the default anyway) the equation actually is 
typeset in
Palatino italics:
.EQ
gfont I
E = m cdot c sup 2
.EN
Requesting any other font except PI seems to work as expected, e.g. \*Qgfont 
NI\*U works
just fine:
.EQ
gfont NI
E = m cdot c sup 2
.EN
.LP
Looking at the eqn preprocessor output, the proximal cause of the problem is 
that
eqn generates
.DS
.CW ".ft \\\(*P
.DE
where actually
.DS
.CW ".ft PI
.DE
should appear and troff than issues a
.DS
.CW "warning: can't find font '\\\(*P'
.DE
.\"----------------------------------------------------------------------

as far as I can see, it is an error that eqn inserts those

.ft \(*P

requests (and troff correspondingly complains about them).


can you confirm the above described behaviour? is this the bug or my fault?

thx,
joerg