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I need to construct an arc depending on a variable. Some lines of the code work some do not. Any ideas?




% works
\draw[->] (0,0) arc (-90:90:.5*\BLS) ;

% works
\draw[->] (0,0) arc (-90:90:\BLS{} and 2cm) ;

% don't work
\draw[->] (0,0) arc (-90:90:.5*\BLS{} and 2cm) ;

% don't work
\draw[->] (0,0) arc (-90:90:.5*\BLS and \BLS) ;


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up vote 3 down vote accepted


\draw[->] (0,0) arc (-90:90:{.5*\BLS} and 2cm);   
\draw[->] (0,0) arc (-90:90:{.5*\BLS} and \BLS);
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Or use:

\draw[->] (0,0) arc (-90:90:\BLS{}/2 and 2cm) ;
\draw[->] (0,0) arc (-90:90:\BLS/2 and \BLS) ;
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Just another way:

\draw[->] (0,0) arc (-90:90:\dimexpr.5\BLS\relax\space and 2cm) ;
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The extra keystrokes are not deliberately added. – kiss my armpit Apr 28 '14 at 19:24

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