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Re: Pi is Rotten? [message #88055 is a reply to message #88044]

Sun, 16 March 2014 13:10

Jim Pendleton
Messages: 165
Registered: November 2011

Senior Member

On Friday, March 14, 2014 7:17:51 AM UTC-6, David Fanning wrote:
> Folks,
>
>
>
> Perhaps because today is Pi Day:
>
>
>
> http://bit.ly/1lDkQi4
>
>
>
> Andrew Cools alerts me to an IDL problem of utmost importance. I refer,
>
> of course, to an inexplicable problem with IDL's version of Pi:
>
>
>
> IDL> print, !dpi, format='(f0.18)'
>
> 3.1415926535897931
>
>
>
> As everyone knows, the actual value of Pi is 3.1415926535897932. The
>
> last digit here is a "2", not a "1".
>
>
>
> http://bit.ly/1qCvycp
>
>
>
> Even ExelisVis itself realizes this, and puts the proper value in the
>
> new !Const system variable. What's up with this? Can we ever trust IDL
>
> again?
>
>
>
> Cheers,
>
>
>
> David
>
>
>
> P.S. Let's just say I'm off to get a piece of apple with my morning Joe.
>
>
>
> --
>
> David Fanning, Ph.D.
>
> Fanning Software Consulting, Inc.
>
> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
>
> Sepore ma de ni thue. ("Perhaps thou speakest truth.")

David,
You might consider updating your Sky is Falling article to include a discussion on the new "implied print" behavior of IDL 8.3.

"For floating-point data types, unlike the PRINT procedure, Implied Print will automatically use the maximum number of digits of precision."

Will it prevent angry phone calls from researchers at 3 am? Probably not.

Jim P.

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[Message index]

		Pi is Rotten? By: David Fanning on Fri, 14 March 2014 06:17
		Re: Pi is Rotten? By: Norbert Hahn on Fri, 14 March 2014 09:08
		Re: Pi is Rotten? By: David Fanning on Fri, 14 March 2014 09:16
		Re: Pi is Rotten? By: Dick Jackson on Fri, 14 March 2014 11:30
		Re: Pi is Rotten? By: Jim Pendleton on Sun, 16 March 2014 13:10

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