Like
Float.compare(a. b) and
Double.compare(a, b)
2015-04-21 17:14 GMT+03:00 John Caron <caron@xxxxxxxx>:
> ok, and you always have to compare floats with a tolerance, not exact. ive
> been bitten many times by that.
>
> John
>
> On Tue, Apr 21, 2015 at 8:02 AM, Daniele Romagnoli
> <daniele.romagnoli@xxxxxxxxxxxxxxxx> wrote:
>>
>> Hi John,
>> thanks for your reply.
>>
>> The problem I have with this is that I'm setting up a predefined set of
>> custom CoordinateReferenceSystem definitions:
>> as an instance, a LambertConformal projection where standard parallels is
>> 25.
>> Then, I'm parsing the gridMapping attributes in order to try to recognize
>> a known custom CRS and I'm getting no matches since it is expecting 25
>> instead of 25.00002. (CRS matching checks use WKT parsing).
>>
>> In the meantime, I will investigate more on this.
>> Cheers,
>> Daniele
>>
>>
>>
>> ==
>> GeoServer Professional Services from the experts! Visit
>> http://goo.gl/NWWaa2 for more information.
>> ==
>>
>> Ing. Daniele Romagnoli
>> Senior Software Engineer
>>
>> GeoSolutions S.A.S.
>> Via Poggio alle Viti 1187
>> 55054 Massarosa (LU)
>> Italy
>> phone: +39 0584 962313
>> fax: +39 0584 1660272
>>
>> http://www.geo-solutions.it
>> http://twitter.com/geosolutions_it
>>
>> -------------------------------------------------------
>>
>> AVVERTENZE AI SENSI DEL D.Lgs. 196/2003
>>
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>>
>>
>>
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>>
>> On Tue, Apr 21, 2015 at 2:15 AM, John Caron <caron@xxxxxxxx> wrote:
>>>
>>> Hi Daniele:
>>>
>>> GRIB projection info is stored in the GRIB file in (at most) 3 bytes, so
>>> has a maximum precision of 24 bits.
>>>
>>> Im surprised that you are seeing a problem, it seems unlikely that a
>>> roundoff in the low order bit of a float should matter.
>>>
>>> But theres not really a good reason that we couldnt use doubles if
>>> needed.
>>>
>>> John
>>>
>>>
>>> On Mon, Apr 20, 2015 at 3:45 AM, Daniele Romagnoli
>>> <daniele.romagnoli@xxxxxxxxxxxxxxxx> wrote:
>>>>
>>>> Hi List,
>>>> I'm using NetCDF Java 4.5.5.
>>>> I have noticed that when computing the LambertConformal projection
>>>> components (such as latin1, latin2...) in Grib1Gds I'm getting:
>>>>
>>>> latin1 = 25.00001
>>>> latin2 = 25.05002
>>>> dx1 = 13.545001
>>>> dy1 = 13.545001
>>>>
>>>> Instead of:
>>>> latin1 = 25
>>>> latin2 = 25.05
>>>> dx1 = 13.545
>>>> dy1 = 13.545
>>>>
>>>> Plus, I'm getting some additional precision loss when extracting these
>>>> attributes
>>>> from the associated grid_mapping variable, as numbers (double values).
>>>> I will surely investigate more on the topic to become more confident
>>>> with that code and I will read again about representation errors on
>>>> floating
>>>> point arithmetics so my question could sounds trivial: Why these variables
>>>> and scale constants are floats instead of doubles? (is it for size and
>>>> performance issues?)
>>>>
>>>> Regards,
>>>> Daniele
>>>>
>>>>
>>>>
>>>>
>>>> ==
>>>> GeoServer Professional Services from the experts! Visit
>>>> http://goo.gl/NWWaa2 for more information.
>>>> ==
>>>>
>>>> Ing. Daniele Romagnoli
>>>> Senior Software Engineer
>>>>
>>>> GeoSolutions S.A.S.
>>>> Via Poggio alle Viti 1187
>>>> 55054 Massarosa (LU)
>>>> Italy
>>>> phone: +39 0584 962313
>>>> fax: +39 0584 1660272
>>>>
>>>> http://www.geo-solutions.it
>>>> http://twitter.com/geosolutions_it
>>>>
>>>> -------------------------------------------------------
>>>>
>>>> AVVERTENZE AI SENSI DEL D.Lgs. 196/2003
>>>>
>>>> Le informazioni contenute in questo messaggio di posta elettronica e/o
>>>> nel/i file/s allegato/i sono da considerarsi strettamente riservate. Il
>>>> loro
>>>> utilizzo è consentito esclusivamente al destinatario del messaggio, per le
>>>> finalità indicate nel messaggio stesso. Qualora riceviate questo messaggio
>>>> senza esserne il destinatario, Vi preghiamo cortesemente di darcene notizia
>>>> via e-mail e di procedere alla distruzione del messaggio stesso,
>>>> cancellandolo dal Vostro sistema. Conservare il messaggio stesso,
>>>> divulgarlo
>>>> anche in parte, distribuirlo ad altri soggetti, copiarlo, od utilizzarlo
>>>> per
>>>> finalità diverse, costituisce comportamento contrario ai principi dettati
>>>> dal D.Lgs. 196/2003.
>>>>
>>>>
>>>>
>>>> The information in this message and/or attachments, is intended solely
>>>> for the attention and use of the named addressee(s) and may be confidential
>>>> or proprietary in nature or covered by the provisions of privacy act
>>>> (Legislative Decree June, 30 2003, no.196 - Italy's New Data Protection
>>>> Code).Any use not in accord with its purpose, any disclosure, reproduction,
>>>> copying, distribution, or either dissemination, either whole or partial, is
>>>> strictly forbidden except previous formal approval of the named
>>>> addressee(s). If you are not the intended recipient, please contact
>>>> immediately the sender by telephone, fax or e-mail and delete the
>>>> information in this message that has been received in error. The sender
>>>> does
>>>> not give any warranty or accept liability as the content, accuracy or
>>>> completeness of sent messages and accepts no responsibility for changes
>>>> made after they were sent or for other risks which arise as a result of
>>>> e-mail transmission, viruses, etc.
>>>>
>>>>
>>>>
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>>>
>>
>
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