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Posted to dev@commons.apache.org by Gilles <gi...@harfang.homelinux.org> on 2015/03/17 13:24:15 UTC
[Math] MATH-1210
Hi.
https://issues.apache.org/jira/browse/MATH-1210
Any objection to applying that patch?
Gilles
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Re: [Math] MATH-1210
Posted by Hank Grabowski <ha...@applieddefense.com>.
No objection, but it might be useful to know which element of the diagonal
caused that as well. For smaller matrices it would be trivial to find but
for larger ones it may take some looking.
On Tue, Mar 17, 2015 at 8:24 AM, Gilles <gi...@harfang.homelinux.org>
wrote:
> Hi.
>
> https://issues.apache.org/jira/browse/MATH-1210
>
> Any objection to applying that patch?
>
> Gilles
>
>
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> To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
> For additional commands, e-mail: dev-help@commons.apache.org
>
>
Re: [Math] MATH-1210
Posted by Phil Steitz <ph...@gmail.com>.
On 3/18/15 5:04 AM, Gilles wrote:
> On Tue, 17 Mar 2015 13:36:36 -0700, Phil Steitz wrote:
>> On 3/17/15 11:23 AM, Gilles wrote:
>>> On Tue, 17 Mar 2015 10:35:15 -0700, Phil Steitz wrote:
>>>> On 3/17/15 5:24 AM, Gilles wrote:
>>>>> Hi.
>>>>>
>>>>> https://issues.apache.org/jira/browse/MATH-1210
>>>>>
>>>>> Any objection to applying that patch?
>>>>
>>>> The error message should be more informative if we are going to
>>>> enrich it. A singularMatrixException with error message "{0} is
>>>> smaller than the minimum ({1})" is a little cryptic.
>>>
>>> For me, it's poor man's logging: the important thing for me is that
>>> one can see what went wrong.
>>
>> We agree on that point - we want people to be able to tell what went
>> wrong. It's really nice when you can do that without looking at
>> the source code. That's where meaningful error messages that make
>> sense in the context where they happen can be useful.
>
> Huge effort on myself to not copy/paste all the arguments from the ML
> archive... :-}
>
>>> But I don't want to rehash that
>>> old discussion. The idea is just to be able to figure out how far
>>> from the threshold the instance falls...
>>>
>>> See my other question (about the covariance matrix) where the
>>> discussion could lead to a more interesting improvement (code,
>>> documentation and error reporting).
>>
>> Yes, that is a good question.
>>>
>>>> It would be
>>>> better to refer to make explicit what quantity is underflowing. I
>>>> agree with Hank that it would also be good to report which element
>>>> of the diagonal was below the threshold.
>>>
>>> This is done in my working copy (with another "cryptic" message).
>>
>> I can't remember how exactly the min QR diag value measures
>> near-singularity. It would be great to at least just report that
>> that is what we are using (instead of determinant or some other
>> measure that one might expect a SingularMatrixException to report as
>> "too small").
>
> The underlying issue (best to discuss on the other thread!) is that
> at this point, it should be (IMHO) kept as an implementation detail
> (where one needs to read the source): a particular decomposition
> method reached its limit, but another might not have. So in addition
> to indicating the low-level source of the failure (with a possibly
> "cryptic", source-related message), I suggest that we devise an
> objective description of why the user's request might be flawed (such
> as an indicator of how close to numerically singular the _matrix_ is,
> not just of how well a decomposition method can cope with it); this
> description deserves a "non-cryptic", high-level, error report.
Yes, and saying something meaningful about how we can tell from the
QR decomp that the matrix is near-singular is exactly what I am
advocating that we do in this case. I don't have time atm to go
back and refresh my knowledge of this, but I will add it to my
personal todo to see if I can improve the error message and / or
consider patches that others may provide.
Phil
>
>
> Gilles
>
>
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> To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
> For additional commands, e-mail: dev-help@commons.apache.org
>
>
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Re: [Math] MATH-1210
Posted by Gilles <gi...@harfang.homelinux.org>.
On Tue, 17 Mar 2015 13:36:36 -0700, Phil Steitz wrote:
> On 3/17/15 11:23 AM, Gilles wrote:
>> On Tue, 17 Mar 2015 10:35:15 -0700, Phil Steitz wrote:
>>> On 3/17/15 5:24 AM, Gilles wrote:
>>>> Hi.
>>>>
>>>> https://issues.apache.org/jira/browse/MATH-1210
>>>>
>>>> Any objection to applying that patch?
>>>
>>> The error message should be more informative if we are going to
>>> enrich it. A singularMatrixException with error message "{0} is
>>> smaller than the minimum ({1})" is a little cryptic.
>>
>> For me, it's poor man's logging: the important thing for me is that
>> one can see what went wrong.
>
> We agree on that point - we want people to be able to tell what went
> wrong. It's really nice when you can do that without looking at
> the source code. That's where meaningful error messages that make
> sense in the context where they happen can be useful.
Huge effort on myself to not copy/paste all the arguments from the ML
archive... :-}
>> But I don't want to rehash that
>> old discussion. The idea is just to be able to figure out how far
>> from the threshold the instance falls...
>>
>> See my other question (about the covariance matrix) where the
>> discussion could lead to a more interesting improvement (code,
>> documentation and error reporting).
>
> Yes, that is a good question.
>>
>>> It would be
>>> better to refer to make explicit what quantity is underflowing. I
>>> agree with Hank that it would also be good to report which element
>>> of the diagonal was below the threshold.
>>
>> This is done in my working copy (with another "cryptic" message).
>
> I can't remember how exactly the min QR diag value measures
> near-singularity. It would be great to at least just report that
> that is what we are using (instead of determinant or some other
> measure that one might expect a SingularMatrixException to report as
> "too small").
The underlying issue (best to discuss on the other thread!) is that
at this point, it should be (IMHO) kept as an implementation detail
(where one needs to read the source): a particular decomposition
method reached its limit, but another might not have. So in addition
to indicating the low-level source of the failure (with a possibly
"cryptic", source-related message), I suggest that we devise an
objective description of why the user's request might be flawed (such
as an indicator of how close to numerically singular the _matrix_ is,
not just of how well a decomposition method can cope with it); this
description deserves a "non-cryptic", high-level, error report.
Gilles
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Re: [Math] MATH-1210
Posted by Phil Steitz <ph...@gmail.com>.
On 3/17/15 11:23 AM, Gilles wrote:
> On Tue, 17 Mar 2015 10:35:15 -0700, Phil Steitz wrote:
>> On 3/17/15 5:24 AM, Gilles wrote:
>>> Hi.
>>>
>>> https://issues.apache.org/jira/browse/MATH-1210
>>>
>>> Any objection to applying that patch?
>>
>> The error message should be more informative if we are going to
>> enrich it. A singularMatrixException with error message "{0} is
>> smaller than the minimum ({1})" is a little cryptic.
>
> For me, it's poor man's logging: the important thing for me is that
> one can see what went wrong.
We agree on that point - we want people to be able to tell what went
wrong. It's really nice when you can do that without looking at
the source code. That's where meaningful error messages that make
sense in the context where they happen can be useful.
> But I don't want to rehash that
> old discussion. The idea is just to be able to figure out how far
> from the threshold the instance falls...
>
> See my other question (about the covariance matrix) where the
> discussion could lead to a more interesting improvement (code,
> documentation and error reporting).
Yes, that is a good question.
>
>> It would be
>> better to refer to make explicit what quantity is underflowing. I
>> agree with Hank that it would also be good to report which element
>> of the diagonal was below the threshold.
>
> This is done in my working copy (with another "cryptic" message).
I can't remember how exactly the min QR diag value measures
near-singularity. It would be great to at least just report that
that is what we are using (instead of determinant or some other
measure that one might expect a SingularMatrixException to report as
"too small").
Phil
>
>
> Gilles
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
> For additional commands, e-mail: dev-help@commons.apache.org
>
>
---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
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Re: [Math] MATH-1210
Posted by Gilles <gi...@harfang.homelinux.org>.
On Tue, 17 Mar 2015 10:35:15 -0700, Phil Steitz wrote:
> On 3/17/15 5:24 AM, Gilles wrote:
>> Hi.
>>
>> https://issues.apache.org/jira/browse/MATH-1210
>>
>> Any objection to applying that patch?
>
> The error message should be more informative if we are going to
> enrich it. A singularMatrixException with error message "{0} is
> smaller than the minimum ({1})" is a little cryptic.
For me, it's poor man's logging: the important thing for me is that
one can see what went wrong. But I don't want to rehash that
old discussion. The idea is just to be able to figure out how far
from the threshold the instance falls...
See my other question (about the covariance matrix) where the
discussion could lead to a more interesting improvement (code,
documentation and error reporting).
> It would be
> better to refer to make explicit what quantity is underflowing. I
> agree with Hank that it would also be good to report which element
> of the diagonal was below the threshold.
This is done in my working copy (with another "cryptic" message).
Gilles
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Re: [Math] MATH-1210
Posted by Phil Steitz <ph...@gmail.com>.
On 3/17/15 5:24 AM, Gilles wrote:
> Hi.
>
> https://issues.apache.org/jira/browse/MATH-1210
>
> Any objection to applying that patch?
The error message should be more informative if we are going to
enrich it. A singularMatrixException with error message "{0} is
smaller than the minimum ({1})" is a little cryptic. It would be
better to refer to make explicit what quantity is underflowing. I
agree with Hank that it would also be good to report which element
of the diagonal was below the threshold.
Phil
>
> Gilles
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
> For additional commands, e-mail: dev-help@commons.apache.org
>
>
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