Desiree,
I think you might be having problems with the resolution of floating-point
values in Java. Differences in the coordinate values are very close to the
resolution of the Java "float" primitive type.
>Date: Fri, 6 Jul 2001 17:20:31 +0200 (MET DST)
>From: Desiree Hilbring <hilbring@xxxxxxxxxxxxxxxxxxxx>
>To: Ugo Taddei <p6taug@xxxxxxxxxxxxxxxxx>
>Subject: Test-Case GriddedTo2DSet
The above message contained the following:
> import visad.*;
> import visad.java2d.DisplayImplJ2D;
> import java.rmi.RemoteException;
> import java.awt.*;
> import javax.swing.*;
> import java.awt.event.*;
> import visad.java3d.DisplayImplJ3D;
>
>
> public class DGM1{
>
> // Declare variables
> // The domain quantities longitude and latitude
> // and the dependent quantities altitude, temperature
>
> private RealType eastValues,northValues;
> private RealType heightValues;
>
> // Two Tuples: one to pack longitude and latitude together, as the domain
> // and the other for the range (altitude, temperature)
> private RealTupleType domain_tuple;
>
> // The function (domain_tuple -> range_tuple )
> private FunctionType func_en_h;
>
> // Our Data values for the domain are represented by the Set
> private Set domain_set;
>
> // The Data class FlatField
> private FlatField vals_ff;
>
> // The DataReference from data to display
> private DataReferenceImpl data_ref;
>
> // The 2D display, and its the maps
> private DisplayImpl display;
> private ScalarMap eastMap, northMap, heightMap;
>
> public DGM1(String []args)
> throws RemoteException, VisADException {
>
> float[] eastNaN =
> {3479991.5f,3479991.5f,3479991.5f,3479991.5f,3479991.5f,
>
> 3479992.5f,3479992.5f,3479992.5f,3479992.5f,3479992.5f,
The difference between these values is perilously close to the
resolution of the IEEE 754-1985 format for single-precision Java
floating-point values (approximately 1 part in 3.5e6). You might think
about adjusting them or using double[] arrays.
>
> 3479993.5f,3479993.5f,3479993.5f,3479993.5f,3479993.5f,
>
> 3479994.5f,3479994.5f,3479994.5f,3479994.5f,3479994.5f,
>
> 3479995.5f,3479995.5f,3479995.5f,3479995.5f,3479995.5f,
>
> 3479996.5f,3479996.5f,3479996.5f,3479996.5f,3479996.5f,
>
> 3479997.5f,3479997.5f,3479997.5f,3479997.5f,3479997.5f,
>
> 3479998.5f,3479998.5f,3479998.5f,3479998.5f,3479998.5f,
>
> 3479999.5f,3479999.5f,3479999.5f,3479999.5f,3479999.5f};
> float[] northNaN =
> {5417829.5f,5417830.5f,5417831.5f,5417832.5f,5417833.5f,
The comment about resolution is relevant for this variable as well.
>
> 5417829.5f,5417830.5f,5417831.5f,5417832.5f,5417833.5f,
>
> 5417829.5f,5417830.5f,5417831.5f,5417832.5f,5417833.5f,
>
> 5417829.5f,5417830.5f,5417831.5f,5417832.5f,5417833.5f,
>
> 5417829.5f,5417830.5f,5417831.5f,5417832.5f,5417833.5f,
>
> 5417829.5f,5417830.5f,5417831.5f,5417832.5f,5417833.5f,
>
> 5417829.5f,5417830.5f,5417831.5f,5417832.5f,5417833.5f,
>
> 5417829.5f,5417830.5f,5417831.5f,5417832.5f,5417833.5f,
>
> 5417829.5f,5417830.5f,5417831.5f,5417832.5f,5417833.5f};
> float[] heightNaN = {245.65f,200.0f,200.0f,200.0f,200.0f,
> 245.65f,200.0f,200.0f,200.0f,200.0f,
> 245.68f,245.66f,200.0f,200.0f,200.0f,
> 245.64f,245.64f,200.0f,200.0f,200.0f,
> 245.63f,245.65f,245.63f,200.0f,200.0f,
> 245.62f,245.65f,245.63f,200.0f,200.0f,
> 245.60f,245.62f,245.63f,245.59f,200.0f,
> 245.60f,245.62f,245.63f,245.59f,200.0f,
> 245.58f,245.57f,245.62f,245.64f,245.54f};
>
>
>
> int nCols = 9;
> int nRows = 5;
> double[][] coords = new double[2][nCols*nRows];
> for (int i=0;i<(nCols*nRows);i++) {
> coords[0][i]=eastNaN[i];
> coords[1][i]=northNaN[i];
> }
...
Because the float values are being transferred to a double array,
there's no reason that I can see not to specify the float values as
double to begin with.
Regards,
Steve Emmerson <http://www.unidata.ucar.edu>
