       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
>>
>

```

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