added # characters when filling paragraph

[Joe Corneli <jcorneli@math.utexas.edu>]

In GNU Emacs 21.3.1 (i386-pc-linux-gnu, X toolkit)
 of 2003-10-31 on raven, modified by Debian
configured using `configure  i386-linux --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib --localstatedir=/var/lib --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes --without-gif --with-x=yes --with-x-toolkit=athena --without-toolkit-scroll-bars'
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: nil

====================================================================================================

I have defined the following function:

(defun fill-in (num-columns)
"Set the fill column and fill everything to the specified column."
(interactive "nFill column: ")
(mark-whole-buffer)
(set-fill-column num-columns)
(fill-individual-paragraphs (point) (mark)))

Running this with argument 10 on a buffer with text

\newcommand{\aff}[2]{\mathfrak{aff}_{#1}
#2} \newcommand{\ala}{\emph{\'a la}}

produces

\newcommand{\aff}[2]{\mathfrak{aff}_{#1}
#2}
#\newcommand{\ala}{\emph{\'a
#la}}