Re: Canceling common primes with strikeout

[Mojca Miklavec <mojca.miklavec.lists@gmail.com>]

David Arnold wrote:
> All,
>
> Anyone have a nice technique to "strike out" the common primes using
> the color red?
>
> \placeformula[-]
> \startformula
>    \frac{12}{18}=\frac{2\cdot2\cdot3}{2\cdot3\cdot3}=\frac23
> \stopformula

A simple solution:

\defineoverlay[strikeme][{\color[red]{\bf/}}]
\def\strikeout#1{\mframed[frame=off,background={foreground,strikeme}]{#1}}

will draw bold red slashes over the numbers. They still seem a bit too
thin too me , but you could use other bolder characters if needed.

A more complex solution with metafun:

\startuniqueMPgraphic{strikeme}
	draw (0,0)--(OverlayWidth,OverlayHeight) withpen pencircle scaled 3pt
withcolor red;
\stopuniqueMPgraphic
\defineoverlay[strikeme][\uniqueMPgraphic{strikeme}]
\def\strikeout#1{\mframed[frame=off,background=strikeme]{#1}}

Usage:

\startformula  
\frac{12}{18}=\frac{\strikeout{2}\cdot2\cdot\strikeout{3}}{\strikeout{2}\cdot\strikeout{3}\cdot3}=\frac23
\stopformula

Mojca