| Re: Quadruple Precision? [message #3367] |
Thu, 19 January 1995 05:40 |
sterner
Messages: 106
Registered: February 1991
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Senior Member |
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chris@mercury.sfsu.edu (Christopher McCarthy) writes:
> Is quadruple precision possible in IDL? EG. what I believe would be:
> real *16 in FORTRAN.
> On my machine (Sparc 1) double precision seems to be good to ~16 digits.
> (IDL's !dpi differed from Mathmatica's pi (to 30 placed) in the 16th digit.
> No I haven't bothered to look up the real pi to check mathmatica!)
> Any thoughts? Thanks.
Let me point you to the Pi Page:
http://www.ccsf.caltech.edu/~roy/pi.html
Here is a small extract from the 50,000 digit subpage:
3.
141592653589793238462643383279502884197169399375105820974944
592307816406286208998628034825342117067982148086513282306647
093844609550582231725359408128481117450284102701938521105559
644622948954930381964428810975665933446128475648233786783165
271201909145648566923460348610454326648213393607260249141273
724587006606315588174881520920962829254091715364367892590360
011330530548820466521384146951941511609433057270365759591953
092186117381932611793105118548074462379962749567351885752724
891227938183011949129833673362440656643086021394946395224737
190702179860943702770539217176293176752384674818467669405132
There is also a link to a 1,250,000 digit page if 50,000
are not enough.
Ray Sterner sterner@tesla.jhuapl.edu
The Johns Hopkins University North latitude 39.16 degrees.
Applied Physics Laboratory West longitude 76.90 degrees.
Laurel, MD 20723-6099
WWW Home page: ftp://fermi.jhuapl.edu/www/s1r/people/res/res.html
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| Re: Quadruple Precision? [message #3370 is a reply to message #3367] |
Wed, 18 January 1995 13:54  |
chris
Messages: 22
Registered: October 1994
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Junior Member |
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I wrote:
Quadruple precision?
The answer is: Nope.
++++++++++++++++++++++++++
IDL does not support quadruple precision. The data type supported
by IDL are listed in Chapter 1 of the IDL User's Guide. The highest
precision floating point numbers in IDL are double precision.
I noticed that you are not listed in our database of IDL users.
We do ask that IDL users who call or write for technical assistance
be registered for IDL Technical Support. In order to receive
further assistance from the technical support group please write
to Donna, donna@rsinc.com for details on purchasing this service.
Sincerely,
Hilary
+-------------------------------------------------------+
| support@rsinc.com | IDL and ENVI |
| 303-786-9930 x320 | Technical Support |
+-------------------------------------------------------+
+++++++++++++++++++++++++++
Yes is was for a non graphical application. I need to know Julian
Date (which ranges around 2e6) to about 12 decimal places, so
a total of ~18 sig figs, for purposes of comparison w/ a Fortran
program. I can get around the problem by using modified julian
dates or separating JD into an integer and a fraction, but I was
looking for an easier way.
-chris
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