Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2012

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

Search the Archive

Re: more plotting peculiarities

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124106] Re: [mg124075] more plotting peculiarities
  • From: Richard Fateman <fateman at eecs.berkeley.edu>
  • Date: Mon, 9 Jan 2012 03:17:30 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201201080922.EAA01272@smc.vnet.net> <4F09EDC6.8020206@math.umass.edu>

On 1/8/2012 11:25 AM, Murray Eisenberg wrote:
> Those results are wholly unsurprising (Version 8). After all, look at 
> some sampled values in the domains, e.g.:
>
>   1.0 + 2.0^-47 Range[-5, 5, .1] // NumberForm[#, 15] &
>   1.02 + 2.0^-47 Range[-5, 5, .1] // NumberForm[#, 15] &
>
> And then take Cos of each list.

OK, then explain why 1.0  vs 1.02 makes a huge difference. Do you not 
find that surprising?
>
> Actually, the plot from the first expression does NOT look empty to 
> me: I see a thickened horizontal axis located at height y = 0.54.
Yes, I saw that too.  The plot looks empty, though.  It certainly is 
highly uninformative.

> Using option AxesOrigin -> {0,0} reveals what appears to be a line at 
> that height.
>
> And the plot from the second is essentially a linearization, given 
> that its range is from around 0.523365951251619 to 0.52336595125168.
Yes, actually what I expect from a normal plotting program is steps that 
illustrate the discretization of the function values to
particular machine floating point numbers.  How do you suggest doing 
that with Mathematica?
>
> On 1/8/12 4:22 AM, Richard Fateman wrote:
>> Plot[Cos[1.0 + n*2.0^-47], {n, -5, 5}]  looks empty
>>
>> Plot[Cos[1.02 + n*2.0^-47], {n, -5, 5}]
>>     looks like a straight line with slope about -1
>>
>> version 7
>>
>




  • Prev by Date: Re: Re: SortBy for multiple key sorts
  • Next by Date: Re: Can't use subscripted variables in function definition?
  • Previous by thread: Re: more plotting peculiarities
  • Next by thread: Re: more plotting peculiarities