On Jul 13, 2004, at 2:53 AM, Christian F. Beckmann wrote:
> Hi
>
> can you please email the report.log file. It seems that the SVD fails.
> This can happen for mainly two reasons- i) the image dimensions are
> wrong (did you use avwmerge -t ?) or (ii) the image intensities are too
> similar (e.g. because the data has been converted to int). You can
> check these things using avwsize, avwstats and/or by loading the data
> into fslview. If you put the data somewhere for me to d/l I'll have a
> quick llook
> cheers
> c
>
>
> On 13 Jul 2004, at 03:03, Dhananjay Thiruvady wrote:
>
>> Christian,
>>
>> This is going back a few weeks ago. I am attempting to identify the
>> independent components in a group of images. This is the error I get
>> after using avwmerge:
>>
>> Starting PCA ...
>>
>> An exception has been thrown
>> Runtime error:- detected by Newmat: process fails to converge
>>
>> MatrixType = Diag # Rows = 2; # Cols = 2; lower BW = 0; upper BW = 0
>> Trace: Evalue(tql2).
>>
>> Does this imply that the independent components cannot be identified?
>>
>> Regards,
>>
>> DJ
>>
>> Christian Beckmann <[log in to unmask]> wrote:
>>> DJ
>>>
>>> time series analysis requires time series - all our functional tools
>>> work
>>> on 4D files. It seems that you've been trying to run it on a single
>>> 3D
>>> volume:
>>>
>>>> Melodic Version 2.0
>>>>
>>>> Melodic results will be in /home/norm_volumes_1/nepi_vol_0002.ica
>>>>
>>>> Reading data file filtered_func_data ... done
>>>> Create mask ... done
>>>> Excluding voxels with constant value
>>>> Data size : 1 x 510340
>>>
>>> You will need to create a 4d file first (avwmerge -t does this). If
>>> the
>>> file should have been 4D already, check the header information
>>> (avwhd) to
>>> see why it appears as a 3d volume
>>>
>>> ta
>>> c
>>>
> --
> Christian F. Beckmann
> Oxford University Centre for Functional
> Magnetic Resonance Imaging of the Brain,
> John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
> Email: [log in to unmask] - http://www.fmrib.ox.ac.uk/~beckmann/
> Phone: +44(0)1865 222782 Fax: +44(0)1865 222717
>
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