corrupted Low-Hi values in SampledSet

• To: visad-list@xxxxxxxxxxxxx
• Subject: corrupted Low-Hi values in SampledSet
• From: "Letourneau, Sylvain" <Sylvain.Letourneau@xxxxxx>
• Date: Thu, 30 May 2002 01:11:05 -0400

Hi,

I got a NullPointerException during interpolation (with the evaluate method)
and finally found out that the error was due to a bad LowX value in my
Irregular1DSet. The problem seems to be related to the use of extreme values
(e.g. Float.MIN_VALUES, Float.MAX_VALUE) as samples for the set but doesn't
happen in a consistent manner.  Please find below a small program which
illustrates the problem:
1- method test1() provides an example for which the Low value gets corrupted
2- method test2() provides a similar example but for which the Low and Hi
values are correct
3- method test3() generates the NullPointerException

The output of the program is:

Test 1: low=-1124.069   hi=3.4028235E38
        aSet is  visad.Irregular1DSet: Dimension = 1 Length = 4
   Dimension 0: Range = -1124.069 to 3.4028235E38

Test 2: low=1.4E-45   hi=3.4028235E38
        aSet is  visad.Irregular1DSet: Dimension = 1 Length = 4
   Dimension 0: Range = 1.4E-45 to 3.4028235E38

Test 3: interField.evaluate(-2000.0f)
java.lang.NullPointerException
        at visad.Irregular1DSet.valueToInterp(Irregular1DSet.java:127)
        at visad.FlatField.resample(FlatField.java:3446)
        at visad.FunctionImpl.evaluate(FunctionImpl.java:169)
        at visad.FunctionImpl.evaluate(FunctionImpl.java:128)
        at TestIrregular1DSet.test3(TestIrregular1DSet.java:51)
        at TestIrregular1DSet.main(TestIrregular1DSet.java:60)
Exception in thread "main" 
Process TestIrregular1DSet exited abnormally with code 1


I got the same error with jdk1.1.3 and jdk1.1.4.  I also replaced
Float.MIN_VALUE by Float.NEGATIVE_INFINITE, no luck. I'm really not
convinced that the problem is in the VisAD logic.  Nevertheless, it would be
good to have a solution.

Thanks,
Sylvain


import java.rmi.RemoteException;
import visad.*;

public class TestIrregular1DSet {

  public TestIrregular1DSet() {
  }

  public void test1() throws VisADException {
         float[][] samples = new float[][] {
                {Float.MIN_VALUE, -1124.06897f, -1047.077026f,
Float.MAX_VALUE}};
         
         Irregular1DSet aSet = new Irregular1DSet(
                RealType.getRealType("x1", null, null), samples);
         float[] hi = aSet.getHi();
         float[] low = aSet.getLow();

         System.out.println("Test 1: low=" + low[0] + "   hi=" + hi[0]);
         System.out.println("        aSet is " + aSet.longString(" "));

  }

  public void test2() throws VisADException {
         float[][] samples = new float[][] {
                {Float.MIN_VALUE, 208.561829f, 326.168915f,
Float.MAX_VALUE}};       
         Irregular1DSet aSet = 
                new Irregular1DSet(RealType.getRealType("x2", null, null),
                samples);

         float[] hi = aSet.getHi();
         float[] low = aSet.getLow();
         System.out.println("Test 2: low=" + low[0] + "   hi=" + hi[0]);
         System.out.println("        aSet is " + aSet.longString(" "));
  }

  public void test3() throws VisADException, RemoteException {
         float[][] samples = new float[][] {
                {Float.MIN_VALUE, -1124.06897f, -1047.077026f,
Float.MAX_VALUE}};
         
         Irregular1DSet aSet = 
                new Irregular1DSet(RealType.getRealType("x1", null,
null),samples);

         RealType x1RT = RealType.getRealType("x1");
         FunctionType interFuncType = 
                new FunctionType(x1RT, RealType.getRealType("value", null,
null));
         FlatField interField = new FlatField(interFuncType, aSet);    
         interField.setSamples(new float[][] {
                {100.0f, 150.0f, 110.0f, 75.0f}});
         System.out.println("Test 3: interField.evaluate(-2000.0f)=");
         System.out.println(interField.evaluate(new Real(x1RT, -2000.0), 
        
Data.WEIGHTED_AVERAGE, 
                                                         Data.NO_ERRORS));
  }

  public static void main(String[] args) throws VisADException,
RemoteException {
         TestIrregular1DSet aTest = new TestIrregular1DSet();
         aTest.test1();
         aTest.test2();
         aTest.test3();   
  }
 
}


===
Sylvain Létourneau 
Research Officer
National Research Council of Canada
1500 Montreal road, Build. M-50, Rm 367A
Ottawa, Ontario Canada K1A 0R6 
Phone:(613) 990-1178 
Fax:(613) 952-0215 

• Follow-Ups:
  • Re: corrupted Low-Hi values in SampledSet
    • From: Bill Hibbard