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I'm trying to include a plot of tan(x) in some student notes.

Here is my input (using ConTeXt):

\usemodule[newmat,tikz,pgfmath] 
\usetikzlibrary[arrows]

\starttext

  \starttikzpicture[scale=0.65]
    \draw[-angle 60] (-9,0) -- (14,0) node[right] {$x$};
    \draw[-angle 60] (0,-6) -- (0,6) node[above] {$y$};
    \foreach \r in
             {-6.28319,-3.14159,0.00000,3.14159,6.28319,9.42478,12.56637}
             \draw[domain=\r-1.4:\r+1.4,line width=2pt] plot[samples=100]
             (\x,{tan(\x r)});
    \foreach \r in
              {-7.8540,-4.7124,-1.5708,1.5708,4.7124,7.8540,10.9956}
              \draw[dashed] (\r,-6) -- (\r,6);    
  \stoptikzpicture

\stoptext

And here is the output:

enter image description here

Can anybody shed some light on this strange output?

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closed as too localized by lockstep, percusse, Paulo Cereda, egreg, Marco Daniel Jan 6 '12 at 23:21

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The output is fine in normal LaTeX. So it seems ConTeXt related. –  Roelof Spijker Dec 16 '11 at 9:36
    
Since tikz uses the same math engine for both LaTeX and ConTeXt, I doubt that this is merely related to ConTeXt. Perhaps it is some bug in the tikz version shipped with ConTeXt - one that does not occur in the version used by whlt3? –  Christian Feuersänger Dec 16 '11 at 9:41
    
This produces the correct output for me on TL 2011, with ConTeXt but it produces a bunch of pgfmath errors in the console output: lots of 'function already exists' errors. So you need to check versions of pgf. –  Alan Munn Dec 16 '11 at 14:50

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