Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2007

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: machine precision number plot fixed in V6?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg83062] Re: [mg83043] machine precision number plot fixed in V6?
  • From: Brett Champion <brettc at wolfram.com>
  • Date: Fri, 9 Nov 2007 05:13:49 -0500 (EST)
  • References: <200711081113.GAA27782@smc.vnet.net>

On Nov 8, 2007, at 5:13 AM , congruentialuminaire at yahoo.com wrote:

> Hello Mathematica UG:
>
> I was doing some work with the PrecisionPlot package (http://
> library.wolfram.com/infocenter/MathSource/715/)
>
> When I ran it under V6, no output was emitted. So I looked again at
> the documentation provided by Ted Ersek. Even though it is 8 years
> old, it contains the following function and plot which does not work
> correctly as recently as V5.
>
> In V6, the invocation with SetPrecision works and emits a smooth plot
> (presumably eliminating the need for this package). Here are the lines
> of code.
>
> -----------------------------------------------------------
> (* a function that does not plot well with machine-precision numbers
> *)
> f2[x_] = ArcSec[x] - Normal[Series[TrigToExp[ArcSec[x]], {x, \
> [Infinity], 7}]]
>
> (* a jagged plot results under V5 and V6 *)
> Plot[f2[t], {t, 25, 40}]
>
> (* a smooth plot results only under V6 *)
> Plot[f2[SetPrecision[t, 17]], {t, 25, 40}]
> ------------------------------------------------------------
>
> If there is a simple explanation for what was fixed in V6 to make this
> work, I am interested to know.

In V6 Plot can take a WorkingPrecision option, so this will also give  
a smooth curve:

Plot[f2[t], {t, 25, 40}, WorkingPrecision -> 17]

Brett Champion
Wolfram Research


  • Prev by Date: Re: StyleSheet Math6 SlideShow: anyone have a nice stylesheet for
  • Next by Date: Re: Can you get a package back to a notebook easily?
  • Previous by thread: machine precision number plot fixed in V6?
  • Next by thread: Re: machine precision number plot fixed in V6?