Re: corrupted Low-Hi values in SampledSet

• To: "Letourneau, Sylvain" <Sylvain.Letourneau@xxxxxx>
• Subject: Re: corrupted Low-Hi values in SampledSet
• From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>
• Date: Thu, 30 May 2002 05:13:06 -0500

Dear Sylvain,

I compiled and ran your test program and did not get any
NullPointerException. In fact, all the results were correct.
Note that Float.MIN_VALUE is the smallest positive float,
rather than the least negative. So in Test1 the low value
is a negative number rather than Float.MIN_VALUE. Here is
the output I got:

  doll% java TestIrregular1DSet
  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)
  missing

Cheers,
Bill


"Letourneau, Sylvain" wrote:
> 
> 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

-- 
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html

• References:
  • corrupted Low-Hi values in SampledSet
    • From: Letourneau, Sylvain