Re: Re: Precision of AiryAi[0.0]
- To: mathgroup at smc.vnet.net
- Subject: [mg103491] Re: [mg103479] Re: Precision of AiryAi[0.0]
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Fri, 25 Sep 2009 05:56:05 -0400 (EDT)
- References: <200909241149.HAA29080@smc.vnet.net>
No, the function is not returning a MachinePrecision number. For
example, note this:
Precision[Nest[Sqrt, AiryAi[0.0], 10^3]]
316.985
As you can see, precision was considerably increased by nesting
square roots. Try it on any MachinePrecision number, you will always
get MachinePrecision numbers.
Andrzej Kozlowski
On 24 Sep 2009, at 20:49, Bill Rowe wrote:
> On 9/23/09 at 7:25 AM, mcmcclur at unca.edu (Mark McClure) wrote:
>
>> Running V7.0.1 on my 64 bit MacBook Pro.
>
>> The result of the simple computation AiryAi[0.0] returns a result
>> with a precision of 15.9, rather than the expected MachinePrecision.
>> That is, we get:
>
>> Precision[AiryAi[0.0]] 15.9546
>
>> Rather than MachinePrecision as in
>
>> Precision[BesselJ[2, 0.0]] MachinePrecision
>
>> Does anyone have an explanation for this?
>
> Notice
>
> In[1]:= {Precision[AiryAi[0.0]],
> Precision[AiryAi[0.0]] == $MachinePrecision}
>
> Out[1]= {15.9546,True}
>
> In[2]:= $Version
>
> Out[2]= 7.0 for Mac OS X x86 (64-bit) (February 19, 2009)
>
> So, why I do not know why this particular function returns the
> numeric value for machine precision rather than simply returning
> MachinePrecision, it is clear that this function is returning a
> machine precision number when given a machine precision number
> as an input.
>
>
- References:
- Re: Precision of AiryAi[0.0]
- From: Bill Rowe <readnews@sbcglobal.net>
- Re: Precision of AiryAi[0.0]