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Re: How to add 'd' to get the correct julian conversion ? [message #33727 is a reply to message #33725]

Thu, 23 January 2003 14:20

Paul Van Delst[1]
Messages: 1157
Registered: April 2002

Senior Member

Kolbjorn Bekkelund wrote:
>
> Craig Markwardt wrote:
>> Kolbjorn Bekkelund <kolbjorn@arctic-linux.tnett.no> writes:
>>
>>
>>> How can I add the NEEDED d to get this:
>>>
>>> 2452662.305203d
>>>
>>> out of this:
>>> maxtime = jul2cal((data(0,maxgust_time)), /TO_STRING, /MDY)
>>>
>>> In my program (data(0,maxgust_time)) fetches 2452662.305203 out of the
>>> array, but if I don't add the d to the julian date it calculates the
>>> wrong time in the above statement.
>>
>>
>> You can use
>> double(data(0,maxgust_time)),
>> but the variable DATA should already be in double precision. At least
>> it should be if you expect 13 decimal digits of precision to be
>> maintained. When you type the number directly on the command line,
>> you probably do have to use the "D" to indicate double precision, but
>> you should not have to if the variable DATA is already double.
>>
>> Craig
>>
>
> I've checked my array a bit more and it seems as if there's something
> wrong with it. From the file I'm reading in with read-ascii I should
> have this:
> 2452662.499876 2.719500 6.216000 343.494000
> 955.793400 93.911600 -5.444307
>
> but the print, data in IDL shows:
> 2.45266e+06 2.71950 6.21600 343.494 955.793
> 93.9116 -5.44431
>
> If I replace the read-acsii with Reimar Bauers read_data_file I get:
> 2452662.5 2.7195000 6.2160000 343.49400
> 955.79340 93.911600 -5.4443070
>
> but as you see the julian date in the first element is wrong in both
> arrays. How can I do ensure that I get all digits inserted ?

If I understand your question (and I'm not sure I do) there _may_ be two things going on
here. David Fanning's post addresses one thing. The other is, if you want to *see* all the
digits on screen, then you must use a format string. A generic "print, data" statements
means that IDL prints out what the IDL-writers thought was a reasonable number of digits
for the data type. If you want something other than the default (i.e. 6 sig figs for your
apparently single precision floating points above), you gotta specify it explicitly using

print, format='(<some useful format descriptor>)', data

paulv

--
Paul van Delst
CIMSS @ NOAA/NCEP/EMC
Ph: (301)763-8000 x7274
Fax:(301)763-8545

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[Message index]

		Re: How to add 'd' to get the correct julian conversion ? By: thompson on Thu, 23 January 2003 15:38
		Re: How to add 'd' to get the correct julian conversion ? By: Paul Van Delst[1] on Thu, 23 January 2003 14:20
		Re: How to add 'd' to get the correct julian conversion ? By: David Fanning on Thu, 23 January 2003 14:15
		Re: How to add 'd' to get the correct julian conversion ? By: Kolbjorn Bekkelund on Thu, 23 January 2003 12:02
		Re: How to add 'd' to get the correct julian conversion ? By: Craig Markwardt on Thu, 23 January 2003 08:46
		Re: How to add 'd' to get the correct julian conversion ? By: David Fanning on Thu, 23 January 2003 08:19
		Re: How to add 'd' to get the correct julian conversion ? By: R.Bauer on Fri, 31 January 2003 10:54

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