[R] netcdf data precision or least significant digit

[Jeff Newmiller]

Correction:

?options (not par)
-- 
Sent from my phone. Please excuse my brevity.

On July 7, 2016 3:26:06 PM PDT, Jeff Newmiller <jdnewmil at dcn.davis.ca.us> wrote:
>Same as with any floating point numeric computation environment... you
>don't. There is always uncertainty in any floating point number... it
>is just larger in this data than you might be used to.
>
>Once you get to the stage where you want to output values, read up on
>
>?round
>?par (digits)
>
>and don't worry about the incidental display of extra digits prior to
>presentation (output). 
>-- 
>Sent from my phone. Please excuse my brevity.
>
>On July 7, 2016 12:50:54 AM PDT, Ismail SEZEN <sezenismail at gmail.com>
>wrote:
>>Hello,
>>
>>I use ncdf4 and ncdf4.helpers packages to get wind data from ncep/ncar
>>reanalysis ncetcdf files. But data is in the form of (9.199998,
>>8.799998, 7.999998, 3.099998, -6.8000018, …). I’m aware of precision
>>and least_significant_digit attributes of ncdf4 object [1]. For uwnd
>>data, precision = 2 and least_significant_digits = 1. My doubt is that
>>should I round data to 2 decimal places or 1 decimal place after
>>decimal point?
>>
>>Same issue is valid for some header info.
>>
>>Output of ncdf4 object:
>>
>>
>>Output of ncdump on terminal:
>>
>>
>>for instance, ncdump's scale factor is 0.01f but ncdf4 object’s
>>scale_factor is 0.00999999977648258. You can notice same issue for
>>actual_range and add_offset. Also a similar issue exist for the data.
>>How can I truncate those extra unsignificant decimal places or round
>>the numbers to significant decimal places?
>>
>>1 -
>>http://www.esrl.noaa.gov/psd/data/gridded/conventions/cdc_netcdf_standard.shtml
>><http://www.esrl.noaa.gov/psd/data/gridded/conventions/cdc_netcdf_standard.shtml>
>>______________________________________________
>>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>https://stat.ethz.ch/mailman/listinfo/r-help
>>PLEASE do read the posting guide
>>http://www.R-project.org/posting-guide.html
>>and provide commented, minimal, self-contained, reproducible code.
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.