Date: Sat, 10 Jul 1999 00:01:41 +0200 (CEST) From: Martin Dieringer <martin@dieringe.dialup.fu-berlin.de> To: Nate Williams <nate@mt.sri.com> Cc: Stephen McKay <syssgm@detir.qld.gov.au>, freebsd-java@FreeBSD.ORG Subject: Re: strange java calculation errors Message-ID: <Pine.BSF.4.10.9907092353330.44163-100000@ThinkPad.nowhere.local> In-Reply-To: <199907091530.JAA05956@mt.sri.com>
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On Fri, 9 Jul 1999, Nate Williams wrote:
> > >I use the latest jdk1.1.8_ELF.V99-6-3.tar.gz with applied net-patch.
> > >On a few-weeks-old 3.2-STABLE.
> > >I have strange arithmetic errors. I sometimes get NaN-s
> > >and very big numbers (...E306) which don't appear on any other machine/os
> > >and don't appear with the linux-jdk1.2 pre-v2.
> >
> > We are getting occasional failures in the GregorianCalendar routines.
> > For some inexplicable reason it is full of floating point calculations.
> > Every so often, one of these calculations is wildly incorrect, and we
> > get an ArrayIndexOutOfBoundsException (when looking up the month in
> > an array). We have a little bit of trace showing one of the statements
> > returning 0 or 9223372036854775807 sometimes (instead of an expected
> > result of a few thousand).
>
> As always, unless we can reproduce this bug, it's almost impossible to
> track down. If you can provide us a test case, there is a very good
> chance we can fix this.
Ok, I set up a sample program. I think it needs to be an awt-application.
I don't get any errors without setVisible(), but with a visible frame
I get errors every few seconds. It has to be a Thread, too, I think.
Probably you know how to track this down further.
Martin
//BugTest.java ----------------------------------------------
import java.awt.*;
import java.util.Random;
public class BugTest extends Frame implements Runnable
{
Random random = new Random();
double weight;
double denom;
double meatEnergy;
double weightgain;
public BugTest(){
setSize(100,100);
setVisible(true);
}
public void run(){
while (true){
try{
calc();
} catch (ArithmeticException a) {
System.err.println("weight: "+ weight + "\ndenom: "+ denom);
a.printStackTrace();
}
}
}
void calc() throws ArithmeticException {
weight = random.nextDouble()*10.;
meatEnergy= 0.029994563969828213;
denom = (.0836 * Math.pow(weight, 1.37));
weightgain = .2849372 * meatEnergy * weight / denom;
if (weightgain > 1000.)
throw new ArithmeticException("weightgain "+weightgain);
}
public static void main(String args[]){
BugTest bug = new BugTest();
Thread bugThread = new Thread(bug);
bugThread.setPriority(Thread.MIN_PRIORITY);
bugThread.start();
}
}
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