2015-05-04 16:20 GMT+02:00 luc <l...@spaceroots.org>:
> Le 2015-05-04 14:32, Benedikt Ritter a écrit :
>
>> Hello Luc,
>>
>> 2015-05-04 13:43 GMT+02:00 <l...@apache.org>:
>>
>> Repository: commons-math
>>> Updated Branches:
>>> refs/heads/master c8cb75243 -> c771c0080
>>>
>>>
>>> Attempt to circumvent some errors which seem to be platform-dependent.
>>>
>>> The Jenkins build often fails on code that seems to be perfectly
>>> correct. Failures also do no always happen so they may depend on
>>> platform. There were similar problems a few months ago that were
>>> probably related to JIT bugs.
>>>
>>> This fix simply tries to do the same thing as before, but with an
>>> earlier detection of NaN in one case, and by comparing directly the bits
>>> representation in another case, to avoid wrong optimizations.
>>>
>>> Project: http://git-wip-us.apache.org/repos/asf/commons-math/repo
>>> Commit:
>>> http://git-wip-us.apache.org/repos/asf/commons-math/commit/c771c008
>>> Tree: http://git-wip-us.apache.org/repos/asf/commons-math/tree/c771c008
>>> Diff: http://git-wip-us.apache.org/repos/asf/commons-math/diff/c771c008
>>>
>>> Branch: refs/heads/master
>>> Commit: c771c0080b08abd80418c4e88f1be3efec828f0a
>>> Parents: c8cb752
>>> Author: Luc Maisonobe <l...@apache.org>
>>> Authored: Mon May 4 13:43:27 2015 +0200
>>> Committer: Luc Maisonobe <l...@apache.org>
>>> Committed: Mon May 4 13:43:27 2015 +0200
>>>
>>> ----------------------------------------------------------------------
>>> .../org/apache/commons/math4/util/FastMath.java | 28
>>> +++++++++-----------
>>> .../apache/commons/math4/util/FastMathTest.java | 4 +--
>>> 2 files changed, 15 insertions(+), 17 deletions(-)
>>> ----------------------------------------------------------------------
>>>
>>>
>>>
>>>
>>> http://git-wip-us.apache.org/repos/asf/commons-math/blob/c771c008/src/main/java/org/apache/commons/math4/util/FastMath.java
>>> ----------------------------------------------------------------------
>>> diff --git a/src/main/java/org/apache/commons/math4/util/FastMath.java
>>> b/src/main/java/org/apache/commons/math4/util/FastMath.java
>>> index 24bb857..fcd03ea 100644
>>> --- a/src/main/java/org/apache/commons/math4/util/FastMath.java
>>> +++ b/src/main/java/org/apache/commons/math4/util/FastMath.java
>>> @@ -315,6 +315,9 @@ public class FastMath {
>>> /** Mask used to clear the non-sign part of a long. */
>>> private static final long MASK_NON_SIGN_LONG = 0x7fffffffffffffffl;
>>>
>>> + /** Bits representation of +1.0. */
>>> + private static final long PLUS_ONE_BITS = 0x3ff0000000000000L;
>>> +
>>> /** 2^52 - double numbers this large must be integral (no fraction)
>>> or NaN or Infinite */
>>> private static final double TWO_POWER_52 = 4503599627370496.0;
>>> /** 2^53 - double numbers this large must be even. */
>>> @@ -1468,6 +1471,10 @@ public class FastMath {
>>> return x;
>>> }
>>>
>>> + if (y != y) { // Y is NaN
>>>
>>>
>> It really took me some time to understand this change. How about using
>> Double.isNaN(double) instead? It does the same as the current code, but
>> reads better, IMHO.
>>
>
> I agree but in this huge class this is how all NaNs are detected and there
> are a bunch of such tests. I don't know the reason these existing tests
> were done this way and not using Double.isNaN, it may well be performance
> related.
> So for this class (and this class only), I prefer to do it the same way it
> is already done a few lines above or below.
>
Yes at first I also thought it has something to do with performance. But
then I looked at the implementation of Double.isNaN(double):
static public boolean isNaN(double v) {
return (v != v);
}
So it's probably because of consistency with the rest of the class. Would
you be willing to merge a PR that changes the whole class to use
Double.isNaN(double) if I provide one?
Benedikt
>
>
> best regards,
> Luc
>
>
>
>
>> Best regards,
>> Benedikt
>>
>>
>> + return y;
>>> + }
>>> +
>>> if (x == 0) {
>>> long bits = Double.doubleToRawLongBits(x);
>>> if ((bits & 0x8000000000000000L) != 0) {
>>> @@ -1485,18 +1492,13 @@ public class FastMath {
>>>
>>> if (y < 0) {
>>> return Double.POSITIVE_INFINITY;
>>> - }
>>> - if (y > 0) {
>>> + } else {
>>> return 0.0;
>>> }
>>>
>>> - return Double.NaN;
>>> }
>>>
>>> if (x == Double.POSITIVE_INFINITY) {
>>> - if (y != y) { // y is NaN
>>> - return y;
>>> - }
>>> if (y < 0.0) {
>>> return 0.0;
>>> } else {
>>> @@ -1505,21 +1507,17 @@ public class FastMath {
>>> }
>>>
>>> if (y == Double.POSITIVE_INFINITY) {
>>> - if (x * x == 1.0) {
>>> - return Double.NaN;
>>> - }
>>> -
>>> - if (x * x > 1.0) {
>>> + long bitsAbsX = MASK_NON_SIGN_LONG &
>>> Double.doubleToRawLongBits(x);
>>> + if (bitsAbsX > PLUS_ONE_BITS) {
>>> return Double.POSITIVE_INFINITY;
>>> - } else {
>>> + } else if (bitsAbsX < PLUS_ONE_BITS) {
>>> return 0.0;
>>> + } else {
>>> + return Double.NaN;
>>> }
>>> }
>>>
>>> if (x == Double.NEGATIVE_INFINITY) {
>>> - if (y != y) { // y is NaN
>>> - return y;
>>> - }
>>>
>>> if (y < 0) {
>>> long yi = (long) y;
>>>
>>>
>>>
>>> http://git-wip-us.apache.org/repos/asf/commons-math/blob/c771c008/src/test/java/org/apache/commons/math4/util/FastMathTest.java
>>> ----------------------------------------------------------------------
>>> diff --git
>>> a/src/test/java/org/apache/commons/math4/util/FastMathTest.java
>>> b/src/test/java/org/apache/commons/math4/util/FastMathTest.java
>>> index 5d36fea..06a1d07 100644
>>> --- a/src/test/java/org/apache/commons/math4/util/FastMathTest.java
>>> +++ b/src/test/java/org/apache/commons/math4/util/FastMathTest.java
>>> @@ -29,8 +29,6 @@ import
>>> org.apache.commons.math4.exception.MathArithmeticException;
>>> import org.apache.commons.math4.random.MersenneTwister;
>>> import org.apache.commons.math4.random.RandomGenerator;
>>> import org.apache.commons.math4.random.Well1024a;
>>> -import org.apache.commons.math4.util.FastMath;
>>> -import org.apache.commons.math4.util.Precision;
>>> import org.junit.Assert;
>>> import org.junit.Before;
>>> import org.junit.Ignore;
>>> @@ -393,6 +391,8 @@ public class FastMathTest {
>>>
>>> Assert.assertTrue("pow(-2.0, 3.5) should be NaN",
>>> Double.isNaN(FastMath.pow(-2.0, 3.5)));
>>>
>>> + Assert.assertTrue("pow(-0.0, NaN) should be NaN",
>>> Double.isNaN(FastMath.pow(-0.0, Double.NaN)));
>>> +
>>> // Added tests for a 100% coverage
>>>
>>> Assert.assertTrue("pow(+Inf, NaN) should be NaN",
>>> Double.isNaN(FastMath.pow(Double.POSITIVE_INFINITY, Double.NaN)));
>>>
>>>
>>>
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