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[netCDFJava #KUD-999886]: Inconsistent results from Array.getDouble()/Array.getFloat()

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  • Subject: [netCDFJava #KUD-999886]: Inconsistent results from Array.getDouble()/Array.getFloat()
  • Date: Thu, 20 Jun 2013 18:31:20 -0600
Hi Aaron:

Ive reproduce the problem and ill let you know when i figure out whats up. 
thanks for the test case.

Jon

> Hello,
> 
> In some cases the netCDF API is returning one value (such as
> "17.699193954467773"), and at other times it is returning another (such
> as "17.000396728515625").  I created a Java main() to reproduce this
> problem independently of ncWMS:
> 
> public static void main( String[] args ) throws Exception{
> //    GridDataset dataset = GridDataset.open(
> "/data/nssl2dMosaic/2013/20130619/v_020500/20130619_v_020500_l_0000000.nc"
> );
> GridDataset dataset = GridDataset.open(
> "/data/nssl2dMosaic/dataset.ncml" );
> GridDatatype grid = null;
> for( GridDatatype thisGrid : dataset.getGrids() ){
> if( thisGrid.getName().equals( "cref" )){
> grid = thisGrid;
> }
> }
> List<Range> ranges = new ArrayList<Range>();
> ranges.add( new Range( 0, 0 ) );
> ranges.add( new Range( 0, 0 ) );
> ranges.add( new Range( 638, 638 ) );
> ranges.add( new Range( 3750, 4622 ) );
> Array arr = grid.getVariable().read( ranges );
> Index index = arr.getIndex();
> index.set( new int[]{0,0,0,834} );
> System.out.println( arr.getDouble( index ) );
> dataset.close();
> }
> 
> Running this program several times will return one of two values: either
> "17.000396728515625" or "17.699193954467773", depending on the run.
> This main() was derived from reverse-engineering the process used by
> ncWMS for accessing my data.  I first encountered this with netCDF API 4.2.
> 
> Another interesting wrinkle is that if I only have the single data file
> (the one with the value accessed by this test - commented out above) in
> the data directory it always returns the "17.0" value.  It is only when
> I have two or more files that match the NCML declaration that
> occasionally it will return different values. Based on this behavior it
> may be an NCML issue and it seems likely that the "17.0" is the correct
> data value.  I ran this with netCDF API 4.3.1.3 I downloaded a few
> minutes ago and it exhibited the same problem.
> 
> The data for this test may be found under
> http://www.ral.ucar.edu/staff/braeckel/nssl2dMosaic/.  Any thoughts on
> what may be going on?
> 
> Thanks,
> Aaron
> 
> 


Ticket Details
===================
Ticket ID: KUD-999886
Department: Support netCDF Java
Priority: Normal
Status: Open