Re: Weird Plot problem
- To: mathgroup at smc.vnet.net
- Subject: [mg59782] Re: Weird Plot problem
- From: Peter Pein <petsie at dordos.net>
- Date: Sun, 21 Aug 2005 03:51:30 -0400 (EDT)
- References: <de6lqh$cfq$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Owen, HL (Hywel) schrieb:
> Hi folks,
>
> I'm seeing a weird plot problem. For reference, I'm using Mathematica 5.2 on Windows XP.
>
> First, using the package
>
> << Statistics`ContinuousDistributions`
>
> I define a Gaussian function modulated with a Sin[] as:
>
> ModulatedGaussian[x_, =EC_, =F3_, modamp_, mod=EB_] := PDF[NormalDistribution[=EC, =F3],x](1 + modamp Sin[2 =F0 x/mod=EB])
>
> I then Plot it using:
>
> Plot[ModulatedGaussian[x, 0.0, 1.0, 0.3, 0.2], {x, -5, 5}]
>
> Instead of seeing the modulation properly, I see the plot available at:
> http://www.astec.ac.uk/staff/owen/pictures/graph.png
>
> Plot[ModulatedGaussian[x, 0.0, 1.0, 0.31, 0.2], {x, -5, 5}]
> and Plot[ModulatedGaussian[x, 0.0, 1.0, 0.29, 0.2], {x, -5, 5}]
> (changing the modulation amplitude) both work fine. Generating the data also works:
>
> ListPlot[Table[{x,ModulatedGaussian[x, 0, 1, 0.3, 0.2]}, {x, -5, 5, 0.01}], PlotJoined -> True]
>
> Anyone else get the same behaviour? Is it a bug?
>
> Cheers,
>
> Hywel
>
> -------------------------------------------
> Hywel Owen h.owen at dl.ac.uk
> Accelerator Science and Technology Centre
> CCLRC Daresbury Laboratory
> United Kingdom
> Tel/Fax: +44 1925 603797/603192
> -------------------------------------------
> "Errors using inadequate data are much less than those using no data at all."
> -- Charles Babbage
>
Hello,
in this case, Mathematica does not evaluate a sufficient number of
points. Add the option PlotPoints->100 to your call to Plot[].
(avoid PlotPoints->27 :-) ).
Peter
--
Peter Pein
Berlin
http://people.freenet.de/Peter_Berlin/
