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Re: Undesired horizontal line in Plot / Bug?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg118178] Re: Undesired horizontal line in Plot / Bug?
  • From: DrMajorBob <btreat1 at austin.rr.com>
  • Date: Fri, 15 Apr 2011 03:57:37 -0400 (EDT)

I see no such thing at my machine.

$Version

"8.0 for Mac OS X x86 (64-bit) (February 23, 2011)"

Bobby

On Thu, 14 Apr 2011 03:48:15 -0500, H Hogreve <hogreve at ifisr.org> wrote:

> A phenomenon that occasionally also occurs in other plots
> can be exemplified by setting
>
> fD[n_, cZ_] := 137^2/Sqrt[1 + cZ^2/(137*n + Sqrt[137^2 - cZ^2])^2];
>
> and plotting, e.g.,
>
> Plot[{fD[1, z], fD[5, z]}, {z, 1, 137}, Frame -> True,
>  PlotRange -> Automatic]
>
> There is a horizonal line visible (parallel to the abscissa)
> that should not be there!! In fact, other plots like, e.g.,
>
> Plot[{fD[1, z], fD[2, z]}, {z, 1, 137}, Frame -> True,
>  PlotRange -> Automatic]
>
> look fine, without this annoying additional line. Unfortunately,
> I could not find a way to remove or suppress this unwanted
> horizontal line in the first plot. Moreover, I observed this
> effect in all versions of Mathematica I have access to at the
> moment, i.e., four, six, and seven, and it makes me wonder
> whether this is a yet unresolved bug.
>
> Thus I would be very grateful for any hints on the questions
>
>   - whether this horizontal line also occurs in the
>     current Mathematica 8.0 ?
>   - is there any remedy to prevent the line from being
>     plotted or to remove it from the plot?
>
> Many thanks in advance for your kind help, H. Hogreve
>
> P.S.: If plotted without Frame, then this line does not
>  occur, but apparently at its position the new abscissa
>  is placed
>


-- 
DrMajorBob at yahoo.com


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