[R] Extending the accuracy of exp(1) in R

[(Ted Harding)]

On 09-Nov-10 13:57:08, Hadley Wickham wrote:
>> Where the value of exp(1) as computed by R is concerned, you have
>> been deceived by what R displays ("prints") on screen. The default
>> is to display any number to 7 digits of accuracy, but that is not
>> the accuracy of the number held internally by R:
>>
>> _exp(1)
>> _# [1] 2.718282
>> _exp(1) - 2.718282
>> _# [1] -1.715410e-07
> 
> I encourage anyone confused about this issue to study
> http://en.wikipedia.org/wiki/The_Treachery_of_Images
> 
> And to watch
> http://www.youtube.com/watch?v=ejweI0EQpX8
> 
> Hadley

"YES"! And to really clinch the point, have a look at:

http://www.preventblindness.org/playitsafe/
teachers_guide_grade3_grade4/paradoxelephant.jpg

and perhaps also my own composition at:

http://www.zen89632.zen.co.uk/Misc/multinecker.pdf

What you *see* in treacherous (or any) images is marks on paper,
or on a computer screen, ...

What you *perceive* is different. Always. (Well, almost always:
you can make a deliberate effort to study the marks on the paper
as marks on paper).

Ted.

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Date: 09-Nov-10                                       Time: 14:57:31
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