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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. > > > _______________________________________________ > netcdf-java mailing list > netcdf-java@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ >
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