[jira] Commented: (MATH-402) Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
[
https://issues.apache.org/jira/browse/MATH-402?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12976047#action_12976047
]
Mikkel Meyer Andersen commented on MATH-402:
I'm also leaning towards agreeing with Phil. It also seems like the user itself
has implemented the change (see
http://code.google.com/p/symja/issues/detail?id=15). Another option is to
postpone to 3.0?
> Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
> -
>
> Key: MATH-402
> URL: https://issues.apache.org/jira/browse/MATH-402
> Project: Commons Math
> Issue Type: Bug
>Affects Versions: 1.2, 2.0, 2.1
> Environment: Issue 15
> http://code.google.com/p/symja/issues/detail?id=15
>Reporter: Axel Kramer
> Fix For: 2.2
>
>
> Why does this unit test in ComplexTest.java gives NaN?
> I expected to get Complex.ZERO as the result?
> {code:java}
>public void testPowZero() {
>TestUtils.assertSame(Complex.NaN,
>Complex.ZERO.pow(Complex.ONE));
> ...
>}
> {code}
> I would suggest something like this for the Complex#pow() method:
> {code:java}
> public Complex pow(Complex x) {
> if (x == null) {
> throw new NullPointerException();
> }
> if (x.imaginary == 0.0) {
> if (real == 0.0 && imaginary == 0.0) {
> if (x.real == 0.0){
> return Complex.ZERO;
> }
> }
> if (x.real == 1.0) {
> return this;
> }
> }
> return this.log().multiply(x).exp();
> }
> {code}
>
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[jira] Commented: (MATH-402) Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
[
https://issues.apache.org/jira/browse/MATH-402?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12970664#action_12970664
]
Phil Steitz commented on MATH-402:
--
I am leaning toward closing as WONTFIX. Going once, going twice...
> Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
> -
>
> Key: MATH-402
> URL: https://issues.apache.org/jira/browse/MATH-402
> Project: Commons Math
> Issue Type: Bug
>Affects Versions: 1.2, 2.0, 2.1
> Environment: Issue 15
> http://code.google.com/p/symja/issues/detail?id=15
>Reporter: Axel Kramer
> Fix For: 2.2
>
>
> Why does this unit test in ComplexTest.java gives NaN?
> I expected to get Complex.ZERO as the result?
> {code:java}
>public void testPowZero() {
>TestUtils.assertSame(Complex.NaN,
>Complex.ZERO.pow(Complex.ONE));
> ...
>}
> {code}
> I would suggest something like this for the Complex#pow() method:
> {code:java}
> public Complex pow(Complex x) {
> if (x == null) {
> throw new NullPointerException();
> }
> if (x.imaginary == 0.0) {
> if (real == 0.0 && imaginary == 0.0) {
> if (x.real == 0.0){
> return Complex.ZERO;
> }
> }
> if (x.real == 1.0) {
> return this;
> }
> }
> return this.log().multiply(x).exp();
> }
> {code}
>
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[jira] Commented: (MATH-402) Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
[
https://issues.apache.org/jira/browse/MATH-402?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12896366#action_12896366
]
Phil Steitz commented on MATH-402:
--
The latest draft ISO C spec appears now to be public and is here:
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1494.pdf
The complex specifications are in Annex G. Does not look like anything has
changed since C99x, though I have not done side-by-side comparisons. It looks
to me like what we have in the code now matches the spec; but the spec does not
specifically call out (unless I missed it) specialization to real arguments.
What is causing the NaN is the singularity in the log function. Colt 1.1
looks like it matches our code. R returns 0 + 0i.
> Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
> -
>
> Key: MATH-402
> URL: https://issues.apache.org/jira/browse/MATH-402
> Project: Commons Math
> Issue Type: Bug
>Affects Versions: 2.2
> Environment: Issue 15
> http://code.google.com/p/symja/issues/detail?id=15
>Reporter: Axel Kramer
>
> Why does this unit test in ComplexTest.java gives NaN?
> I expected to get Complex.ZERO as the result?
> {code:java}
>public void testPowZero() {
>TestUtils.assertSame(Complex.NaN,
>Complex.ZERO.pow(Complex.ONE));
> ...
>}
> {code}
> I would suggest something like this for the Complex#pow() method:
> {code:java}
> public Complex pow(Complex x) {
> if (x == null) {
> throw new NullPointerException();
> }
> if (x.imaginary == 0.0) {
> if (real == 0.0 && imaginary == 0.0) {
> if (x.real == 0.0){
> return Complex.ZERO;
> }
> }
> if (x.real == 1.0) {
> return this;
> }
> }
> return this.log().multiply(x).exp();
> }
> {code}
>
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[jira] Commented: (MATH-402) Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
[
https://issues.apache.org/jira/browse/MATH-402?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12896345#action_12896345
]
Luc Maisonobe commented on MATH-402:
I know we do not follow C99 in many aspects, but what does C99 standard say
about this specific topic ?
> Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
> -
>
> Key: MATH-402
> URL: https://issues.apache.org/jira/browse/MATH-402
> Project: Commons Math
> Issue Type: Bug
>Affects Versions: 2.2
> Environment: Issue 15
> http://code.google.com/p/symja/issues/detail?id=15
>Reporter: Axel Kramer
>
> Why does this unit test in ComplexTest.java gives NaN?
> I expected to get Complex.ZERO as the result?
> {code:java}
>public void testPowZero() {
>TestUtils.assertSame(Complex.NaN,
>Complex.ZERO.pow(Complex.ONE));
> ...
>}
> {code}
> I would suggest something like this for the Complex#pow() method:
> {code:java}
> public Complex pow(Complex x) {
> if (x == null) {
> throw new NullPointerException();
> }
> if (x.imaginary == 0.0) {
> if (real == 0.0 && imaginary == 0.0) {
> if (x.real == 0.0){
> return Complex.ZERO;
> }
> }
> if (x.real == 1.0) {
> return this;
> }
> }
> return this.log().multiply(x).exp();
> }
> {code}
>
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[jira] Commented: (MATH-402) Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
[
https://issues.apache.org/jira/browse/MATH-402?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12896344#action_12896344
]
Phil Steitz commented on MATH-402:
--
Thanks for reporting this. If we do make the suggested change, we need to
change the formulas in the javadoc to reflect the changed definition. The
value returned is a consequence of how we have defined complex exponentiation,
which is spelled out in the javadoc for pow, exp and log. I am open to
changing the definition, but we should make sure that the javadoc is modified
to reflect whatever change we make. Interested in what others think the
definition should be.
> Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
> -
>
> Key: MATH-402
> URL: https://issues.apache.org/jira/browse/MATH-402
> Project: Commons Math
> Issue Type: Bug
>Affects Versions: 2.2
> Environment: Issue 15
> http://code.google.com/p/symja/issues/detail?id=15
>Reporter: Axel Kramer
>
> Why does this unit test in ComplexTest.java gives NaN?
> I expected to get Complex.ZERO as the result?
> {code:java}
>public void testPowZero() {
>TestUtils.assertSame(Complex.NaN,
>Complex.ZERO.pow(Complex.ONE));
> ...
>}
> {code}
> I would suggest something like this for the Complex#pow() method:
> {code:java}
> public Complex pow(Complex x) {
> if (x == null) {
> throw new NullPointerException();
> }
> if (x.imaginary == 0.0) {
> if (real == 0.0 && imaginary == 0.0) {
> if (x.real == 0.0){
> return Complex.ZERO;
> }
> }
> if (x.real == 1.0) {
> return this;
> }
> }
> return this.log().multiply(x).exp();
> }
> {code}
>
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[jira] Commented: (MATH-402) Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
[
https://issues.apache.org/jira/browse/MATH-402?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12896247#action_12896247
]
Axel Kramer commented on MATH-402:
--
Sorry for my stupid suggestion in the first post.
It should be something like this:
{code:java}
public Complex pow(Complex x) {
if (x == null) {
throw new NullPointerException();
}
if (x.real == 0.0 && x.imaginary == 0.0) {
if (real == 0.0 && imaginary == 0.0) {
// 0^0 => NaN
return Complex.NaN;
}
// THIS^0 => 1 for THIS<>0
return Complex.ONE;
}
if (real == 0.0 && imaginary == 0.0) {
// 0^x => 0 for x<>0
return Complex.ZERO;
}
return this.log().multiply(x).exp();
}
{code}
> Complex.ZERO.pow(Complex.ONE) gives NaN in unit tests
> -
>
> Key: MATH-402
> URL: https://issues.apache.org/jira/browse/MATH-402
> Project: Commons Math
> Issue Type: Bug
>Affects Versions: 2.2
> Environment: Issue 15
> http://code.google.com/p/symja/issues/detail?id=15
>Reporter: Axel Kramer
>
> Why does this unit test in ComplexTest.java gives NaN?
> I expected to get Complex.ZERO as the result?
> {code:java}
>public void testPowZero() {
>TestUtils.assertSame(Complex.NaN,
>Complex.ZERO.pow(Complex.ONE));
> ...
>}
> {code}
> I would suggest something like this for the Complex#pow() method:
> {code:java}
> public Complex pow(Complex x) {
> if (x == null) {
> throw new NullPointerException();
> }
> if (x.imaginary == 0.0) {
> if (real == 0.0 && imaginary == 0.0) {
> if (x.real == 0.0){
> return Complex.ZERO;
> }
> }
> if (x.real == 1.0) {
> return this;
> }
> }
> return this.log().multiply(x).exp();
> }
> {code}
>
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