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Re: More Graphic Bugs

  • To: mathgroup at
  • Subject: [mg1216] Re: More Graphic Bugs
  • From: beretta at ATHENA.MIT.EDU (Robert K Beretta)
  • Date: Fri, 26 May 1995 01:29:51 -0400
  • Organization: Massachusetts Institute of Technology

In article <3prs0g$598 at> Xah Y Lee <xyl10060 at> writes:
>Another Bug in Graphics. This one come up totally unexpected. In the 
>following code, you will see a red dot about 25 pixel in diameter at 
>location {4,.5}. WHERE DOES THIS DOT COME FROM?
>Plot[ { Sin@x }, {x,0, 6},
>        AspectRatio->Automatic,
>        PlotRange->All,
>        PlotStyle->{{Hue[0],Thickness[.09]}},
>        Prolog->{Thickness[.04],Line[{{-1,0.5},{4,.5}}]}


I don't know where it comes from, but if you add one more set of curly braces
to the Prolog option setting to isolate it from the other graphics directives 
it will go away.  Apparently, Mma joins the Prolog and Epilog settings to
the beginning and end of the main list of primitives, and then maps the 
PlotStyle directives over everything.  Why this affects only the point at the
end of the line segment, and not the entire line, I haven't a clue.

Patched version of code above:

Plot[ { Sin@x }, {x,0, 6},
        Prolog->{ {Thickness[.04],Line[{{-1,0.5},{4,.5}}]} }

Bob Beretta
beretta at

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