bugGNU Octave - Bugs: bug #57475, svds warns about ill-condition...

 
 

bug #57475: svds warns about ill-condition input with NaNs rather than issuing error

Submitter:  CH <atcl>
Submitted:  Wed 25 Dec 2019 10:12:57 AM UTC
   
 
Category:  Octave Function Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Missed Error or Warning
Status:  Confirmed Assigned to:  None
Originator Name:  Open/Closed:  * Open
Release:  * dev Operating System:  * Any
Fixed Release:  None Planned Release:  None
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Thu 26 Dec 2019 06:46:53 PM UTC, comment #1: 

For reference, the behavior on the development version of Octave which is about to become version 6.1 is a little less scary:


 x = svds(nan*ones(3),2)
warning: svds: returning fewer singular values than requested
warning: called from
    svds at line 230 column 7

x = [](0x1)


Still, it would be better if the warning message was more precise about the problem (NaN).  For reference, Matlab issues the same error for either of your examples (badly-conditioned matrix with Info or NaN present).



Rik <rik5>
Group administrator
Wed 25 Dec 2019 10:12:57 AM UTC, original submission:  

Calling svds on NaN matrix requesting a set number of singular values less than largest dimension of the argument matrix returns:


svds(nan*ones(3),2)
DLASCL: parameter number 4 is invalid
error: Fortran procedure terminated by call to XERBLA
error: called from
    eigs at line 285 column 20
    svds at line 187 column 9


while requesting all singular values gives:


svds(nan*ones(3),3)
error: eig: EIG: matrix contains Inf or NaN values
error: called from
    eigs at line 277 column 22
    svds at line 187 column 9


Does the first error messagee need to be fixed?

Best

CH <atcl>

 

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    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2019-12-26 rik5 StatusNone Confirmed
        Release5.1.0 dev
        Summarysvds returns unusual error svds warns about ill-condition input with NaNs rather than issuing error

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