% cancel.sty version 2.1 12-Mar-2000.
% Donald Arseneau asnd@triumf.ca
% I contribute this software to the public domain. No rights reserved.
%
% Commands:
% ~~~~~~~~~
% \cancel draws a diagonal line (slash) through its argument.
% \bcancel uses the negative slope (a backslash).
% \xcancel draws an X (actually \cancel plus \bcancel).
% \cancelto{<value>}{<expression>} draws a diagonal arrow through the
% expression, pointing to the value.
%
% The first three work in math and text mode, but \cancelto is only
% for math mode.
% The slope of the line or arrow depends on what is being cancelled.
%
% Options:
% ~~~~~~~~
% Bt default, none of these commands affects the horizontal spacing,
% so they might over-print neighboring parts of the formula (or text).
% They do add their height to the expression, so there should never be
% unintended vertical overlap. There is a package option [makeroom] to
% increase the horizontal spacing to make room for the cancellation value.
%
% If you use the color package, then you can declare
% \renewcommand{\CancelColor}{<color_command>}
% and the cancellation marks will be printed in that color (e.g., \blue).
% However, if you are using color, I recommend lightly shaded blocks rather
% than diagonal arrows for cancelling.
%
% The option [thicklines] asks for heavier lines and arrows. This may be
% useful when the lines are colored a light shade.
%
% The size (math style) of the \cancelto value depends on package options
% according to this table:
%
% Current style [samesize] [smaller] [Smaller]
% ------------- ---------------- ---------------- ----------------
% \displaystyle \displaystyle \textstyle \scriptstyle
% \textstyle \textstyle \scriptstyle \scriptstyle
% \scriptstyle \scriptstyle \scriptscriptstyle \scriptscriptstyle
% \scriptscriptstyle \scriptscriptstyle \scriptscriptstyle \scriptscriptstyle
%
% ("smaller" is the default behavior. It gives textstyle limits in
% displaystyle, whereas "Smaller" gives scriptstyle limits.)
%
% This package is provided without guarantees or support. Drawing slashes
% through math to indicate "cancellation" is poor design. I don't recommend
% that you use this package at all.
\ProvidesPackage{cancel}[2000/03/12 v2.1 Cancel math terms]
\newcommand{\CancelColor}{}
\newcommand{\cancelto}{1}% default option = smaller
\let\canto@fil\hidewidth
\let\canc@thinlines\thinlines
\DeclareOption{samesize}{\def\cancelto{999}}
\DeclareOption{smaller}{\def\cancelto{1}}
\DeclareOption{Smaller}{\def\cancelto{0}}
\DeclareOption{makeroom}{\def\canto@fil{\hfil}}
\DeclareOption{overlap}{\let\canto@fil\hidewidth}
\DeclareOption{thicklines}{\let\canc@thinlines\thicklines}
\ProcessOptions
\DeclareRobustCommand\cancel[1]{\ifmmode
\mathpalette{\@cancel{\@can@slash{}}}{#1}\else
\@cancel{\@can@slash{}}\hbox{#1}\fi}
\DeclareRobustCommand\bcancel[1]{\ifmmode
\mathpalette{\@cancel{\@can@slash{-}}}{#1}\else
\@cancel{\@can@slash{-}}\hbox{#1}\fi}
\DeclareRobustCommand\xcancel[1]{\ifmmode
\mathpalette{\@cancel{\@can@slash{+}\@can@slash{-}}}{#1}\else
\@cancel{\@can@slash{+}\@can@slash{-}}\hbox{#1}\fi}
\newcommand\@cancel[3]{%
\@begin@tempboxa\hbox{\m@th$#2{#3}$}%
\dimen@\height
\setbox\@tempboxa\hbox{$\m@th\vcenter{\box\@tempboxa}$}%
\advance\dimen@-\height % the difference in height
\unitlength\p@ \canc@thinlines
{\/\raise\dimen@\hbox{\ooalign{#1\hfil\box\@tempboxa\hfil \cr}}}%
\@end@tempboxa
}
\def\@can@slash#1{\canto@fil$\m@th \CancelColor\vcenter{\hbox{%
\dimen@\width \@min@pt\dimen@ 2\@min@pt\totalheight6%
\ifdim\totalheight<\dimen@ % wide
\@min@pt\dimen@ 8%
\@tempcnta\totalheight \multiply\@tempcnta 5 \divide\@tempcnta\dimen@
\advance\dimen@ 2\p@ % "+2"
\edef\@tempa{(\ifcase\@tempcnta 6,#11\or 4,#11\or 2,#11\or 4,#13\else 1,#11\fi
){\strip@pt\dimen@}}%
\else % tall
\@min@pt\totalheight8%
\advance\totalheight2\p@ % "+2"
\@tempcnta\dimen@ \multiply\@tempcnta 5 \divide\@tempcnta\totalheight
\dimen@ \ifcase\@tempcnta .16\or .25\or .5\or .75\else 1\fi \totalheight
\edef\@tempa{(\ifcase\@tempcnta 1,#16\or 1,#14\or 1,#12\or 3,#14\else 1,#11\fi
){\strip@pt\dimen@}}%
\fi
\expandafter\line\@tempa}}$\canto@fil \cr}
\ifcase\cancelto
\def\cancelto#1#2{\mathchoice % Smaller option
{\@cancelto\scriptstyle{#1}\displaystyle{#2}}%
{\@cancelto\scriptstyle{#1}\textstyle{#2}}%
{\@cancelto\scriptscriptstyle{#1}\scriptstyle{#2}}%
{\@cancelto\scriptscriptstyle{#1}\scriptscriptstyle{#2}}%
}
\or
\def\cancelto#1#2{\mathchoice % smaller option (default)
{\@cancelto\textstyle{#1}\displaystyle{#2}}%
{\@cancelto\scriptstyle{#1}\textstyle{#2}}%
{\@cancelto\scriptscriptstyle{#1}\scriptstyle{#2}}%
{\@cancelto\scriptscriptstyle{#1}\scriptscriptstyle{#2}}%
}
\else
\def\cancelto#1#2{\mathchoice % samesize option
{\@cancelto\textstyle{#1}\displaystyle{#2}}%
{\@cancelto\textstyle{#1}\textstyle{#2}}%
{\@cancelto\scriptstyle{#1}\scriptstyle{#2}}%
{\@cancelto\scriptscriptstyle{#1}\scriptscriptstyle{#2}}%
}
\fi
\newcommand\@cancelto[4]{%
\@begin@tempboxa\hbox{\m@th$#3{#4}$}%
\dimen@\width % wide
\@min@pt\dimen@ 2\@min@pt\totalheight4
\ifdim\totalheight<\dimen@
\@tempcnta\totalheight \multiply\@tempcnta 5 \divide\@tempcnta\dimen@
\@tempdimb 3\p@ % extra width for arrowhead ("+2")
\advance\dimen@ \ifcase\@tempcnta 5\or 5\or 4\or 3\else 2\fi \p@
\@min@pt\dimen@9\advance\dimen@\p@
\edef\@tempa{\ifcase\@tempcnta 5441\or 5441\or 5421\or 4443\else 3611\fi
{\strip@pt\dimen@}{\strip@pt\@tempdimb}}%
\def\@tempb{Cancel #4 to #2; case wide }%
\else % tall
\advance\totalheight3\p@ % "+2"
\@tempcnta\dimen@ \multiply\@tempcnta 5 \divide\@tempcnta\totalheight
\advance\totalheight3\p@ % "+2"
\dimen@ \ifcase\@tempcnta .25\or .25\or .5\or .75\else 1\fi \totalheight
\@tempdimb \ifcase\@tempcnta .8\or .8\or 1.2\or 1.5\else 2\fi \p@
\edef\@tempa{\ifcase\@tempcnta 0814\or 0814\or 1812\or 2734\else 3611\fi
{\strip@pt\dimen@}{\strip@pt\@tempdimb}}%
\fi
\dimen@\height
\setbox\@tempboxa\hbox{$\m@th\vcenter{\box\@tempboxa}$}%
\advance\dimen@-\height % the difference in height
\unitlength\p@ \canc@thinlines
{\/\raise\dimen@\hbox{\expandafter\canto@vector\@tempa{#1}{#2}}}%
\@end@tempboxa
}
% #1, #2 offset of label #6 extra width to clear arrowhead
% #3, #4 vector direction #7 superscript label style
% #5 vector width #8 superscript label
\def\canto@vector#1#2#3#4#5#6#7#8{%
\dimen@.5\p@
\setbox\z@\vbox{\boxmaxdepth.5\p@
\hbox{\kern-1.2\p@\kern#1\dimen@$#7{#8}\m@th$}}%
\ifx\canto@fil\hidewidth \wd\z@\z@ \else \kern-#6\unitlength \fi
\ooalign{%
\canto@fil$\m@th \CancelColor
\vcenter{\hbox{\dimen@#6\unitlength \kern\dimen@
\multiply\dimen@#4\divide\dimen@#3 \vrule\@depth\dimen@\@width\z@
\vector(#3,#4){#5}%
}}^{\raise#2\dimen@\copy\z@\kern-\scriptspace}$%
\canto@fil \cr
\hfil \box\@tempboxa \kern\wd\z@ \hfil \cr}}
\def\@min@pt#1#2{\ifdim#1<#2\p@ #1#2\p@ \relax\fi}