| Re: CHOLDC failed [message #66780] |
Tue, 09 June 2009 00:00 |
Craig Markwardt
Messages: 1869
Registered: November 1996
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Senior Member |
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On Jun 8, 7:23 am, Prashanth <prashanthred...@gmail.com> wrote:
> Hello!
>
> I already posted this on the IDL forum but with no reply yet.
>
> I have a problem with the error message 'CHOLDC Failed'. I developed a
> small software for automatic change detection. I compiled it and
> started distributing the .sav file to run with the IDL VM. The code
> works perfectly fine on my machine and some other machines I checked
> on. But every now and then some of my colleagues report that its not
> working on their machines. Initially, I thought it might be a Floating
> point problem. I used !Except=0 but this doesn't help.
>
> Any clues on this problem? I understand this is something related to
> hardware but I have no knowledge of these issues.
As Paolo hinted at, it means that your matrix is not positive-definite
to within the numerical precision attainable with your computer.
Sadly, CHOLDC is quite fragile in that respect. You might give a try
with MCHOLDC from my web page...
Craig
P.S. Location of MCHOLDC...
http://cow.physics.wisc.edu/~craigm/idl/math.html
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| Re: CHOLDC failed [message #66790 is a reply to message #66780] |
Mon, 08 June 2009 11:04  |
pgrigis
Messages: 436
Registered: September 2007
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Senior Member |
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Prashanth wrote:
> Hello!
>
> I already posted this on the IDL forum but with no reply yet.
>
> I have a problem with the error message 'CHOLDC Failed'. I developed a
> small software for automatic change detection. I compiled it and
> started distributing the .sav file to run with the IDL VM. The code
> works perfectly fine on my machine and some other machines I checked
> on. But every now and then some of my colleagues report that its not
> working on their machines. Initially, I thought it might be a Floating
> point problem. I used !Except=0 but this doesn't help.
>
> Any clues on this problem? I understand this is something related to
> hardware but I have no knowledge of these issues.
I guess your array may have determinant 0?
Ciao,
Paolo
>
> Best regards,
>
> Prashanth
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