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Re: Re: Combined Set, SetDelayed

  • To: mathgroup at smc.vnet.net
  • Subject: [mg100906] Re: [mg100875] Re: Combined Set, SetDelayed
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Thu, 18 Jun 2009 04:50:55 -0400 (EDT)
  • References: <h0vteh$6v2$1@smc.vnet.net> <h12gck$e8s$1@smc.vnet.net> <h19hur$oqf$1@smc.vnet.net> <200906170835.EAA08294@smc.vnet.net>

On 17 Jun 2009, at 17:35, Helen Read wrote:

> magma wrote:
>> Helen Read wrote:
>>> AES wrote:
>>>> Helen Read <h... at together.net> wrote:
>>>>> 0.811 seconds. The second version, using the function that  
>>>>> remembers
>>>>> values, took only 1.87003*10^-15 seconds.
>>>> The frequency of visible light is around 3*10^14 Hz, so that's  
>>>> around
>>>> one period of a visible light wave.  Is there maybe a typo here?
>>> No, no typo. Not sure what your point is.
>>
>> I think AES point is that this timing figure seems a bit too  
>> unrealistic.
>> I personally got a timing of 1.33357*10^-17 sec. About 100 times  
>> faster!
>> Now, a light signal - regardless of frequency - travels a distance of
>> about 40 angstrom during that time.
>> Is this meaningful or is it just a way for Mathematica to say that  
>> the
>> operation was too fast to be timed properly?
>
> Fair enough, but it wasn't a typo. I was merely reporting  
> Mathematica's
> output.
>
> -- 
> Helen Read
> University of Vermont
>

Chop[1.87003*10^-15]
  0

and that's all there is to it...

Andrzej Kozlowski


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