# [OS X TeX] \Cauchy-Principal-Value-Integral

Bruno Voisin Bruno.Voisin at hmg.inpg.fr
Wed Nov 27 04:16:15 EST 2002


Le mercredi, 27 nov 2002, à 08:12 Europe/Paris, Steffen Lund Hokland a
écrit :

> Does anybody know if there exist a symbol which consists of an
> integral (\int} with a vetically centered horisontal bar. It's quite
> common notation for the Cauchy Principal Value integral, but I can't
> seem to find it in the Not So Short ... or Daly and Kopka: 'A Guide to
> LaTeX.
>
> The alternative, I guess, is to make the d... thing my self....

Or to use this thing I've written:

\newlength{\intwidth}
\DeclareRobustCommand{\fpint}[2]
{\mathop{%
\text{%
\settowidth{\intwidth}{$\int$}%
\makebox[0pt][l]{\makebox[\intwidth]{$-$}}%
$\int_{#1}^{#2}$}}}

It assumes the package amsmath is loaded, so that the command \text can
be used. This \fpint (for "finite part integral") does not work exactly
as \int, it takes the limits as arguments, as in \fpint{0}{\infty}
replacing \int_0^\infty.

The TeXbook says, for such composite symbols, taking \notin as an
example on p. 437 in Appendix F: "The definition of \notin in Appendix
B indicates how similar symbols can be constructed". But in Appendix B,
pp. 360-361 I never managed to understand how the construction works
(especially \c at ncel).

The best solution would of course be special fonts including the
symbol, such as the AMS negated symbol fonts. The finite part integral
is indeed in MathML specification, at slot U02A0D, see:

http://www.w3.org/TR/MathML2/02A.html
http://www.w3.org/TR/MathML2/bycodes.html

It is also included in the font Esstix-Six, available at:

ftp://ftp.elsevier.nl/pub/styles/esstix/esstix.zip

But I'm not aware of any TeX macro package for accessing these fonts.

Michel Bovani (Michel, êtes-vous en ligne ?) did some work earlier this
summer on a set of PostScript mathematical fonts for accompanying
Utopia, and the principal value integral was part of this set.

Good luck,

Bruno Voisin

-----------------------------------------------------
Mac TeX info, resources, and news can be found at:
<http://www.esm.psu.edu/mac-tex/>
-----------------------------------------------------
List archives can be found at:
<http://www.esm.psu.edu/mac-tex/MacOSX-TeX-Digests/>
-----------------------------------------------------
See message headers for list info.
-----------------------------------------------------