[gradsusr] undef bug in grads2!

[Jennifer Adams]

On Oct 11, 2012, at 2:14 PM, Muthuvel Chelliah wrote:

> Hello Bryan and other grads developers,
> 
> First of all thank you for all the great work you folks
> do. You must have heard about several small issues
> in grads2, that are yet to be resolved, for example,
> the lack of regrid2, etc. Because of this, in most
> of CPC operations, we are still using grads version 1.94,
> and not switched to grads2.

Almost all the features of regrid (except the voting) have been incorporated into the lterp function. The documentation for lterp has been updated (http://iges.org/grads/gadoc/gradfunclterp.html), but this capability is not available in a public release yet. There is a build at CPC that you can use to try out the new features. I will send you the location offline. 

> 
> Here is another one to the list of grads 2 problems.
> 
> In grads 2, I opened a file with undef explicitly
> set as  -999.0.
> 
> I defined a variable and computed something,
> and write the values out via fwrite. For some
> reason, it is not using the same undef values
> as it is input control file, but has set the undef as:
> ga-> q undef
> Output undef value is set to -999000000.000000
> 
> I was scratching my head, since it took me
> some time to figure this out.  This is definitely a bug, 
> and please take a look at this.
This is not a bug. It was a required change that goes back to version 2.0.a6 from June of 2009. Here is the notice from the ChangeLog: 
   * New commands "set undef" and "query undef" allow the user to 
      control the undefined data value for all forms of GrADS output. 
      This affects all the undefined values printed to screen in the 
      'gxout stat' and 'gxout print' output, as well as the undefined 
      values in fwrite, sdfwrite, and geotiff files. 
      The default output undef value is -9.99e8.
      N.B. THIS FEATURE CHANGES THE DEFAULT BEHAVIOR OF GrADS! 
The documentation page for 'set undef' is at http://iges.org/grads/gadoc/gradcomdsetundef.html
--Jennifer


> 
> Thanks again for all your great efforts into grads,
> which is greatly appreciated by us all.
> 
> Muthu
> -- 
> ------------------------------------------------------------------
> Dr.Muthuvel Chelliah, eMail:Muthuvel.Chelliah at noaa.gov
> 
> Rm.3008, Climate Prediction Center, Ph:(301) 683-3393
> NCEP/NWS/NOAA/U.S.Dept.of Commerce,
> 5830, University Research Court, NCWCP
> College Park, MD 20740.
> 
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--
Jennifer M. Adams
IGES/COLA
4041 Powder Mill Road, Suite 302
Calverton, MD 20705
jma at cola.iges.org



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