Dear
experts,
I’m
running into an error when running selxavg3. It says the
design is ill-conditioned. I’m a bit stuck, because the same
pipeline works in most subjects, but not all. Also, if I
exchange the functional scan (f.nii.gz) with a scan from a
working session of the same subject (same number of volumes
etc.) I don’t get any errors. I’m grateful for any advice
that helps to track down the mistake I’m doing.
Here
the content of the selxavg3.log file:
cd
/home/hector/SENS_MAPPING_BLOCK/sessions
/opt/software/freesurfer/fsfast/bin/selxavg3-sessbc
-s HEC_035_1 -analysis
MPBDandefs_orig_lhrh_revd11.5_sm2.lh -no-preproc -fwhm
-force
Found
42449/139130 (30.5) voxels in mask
Creating
Design Matrix
...
creation time = 0.004 sec
DoMCFit
= 1
ntptot
= 500, nX = 33, DOF = 467
XCond
= 2.63784e+16 (normalized)
ERROR:
design is ill-conditioned
Before
the error it gives a warning that the design matrix is
singular or badly scaled:
[Warning:
Matrix is close to singular or badly scaled. Results may
be
inaccurate.
RCOND = 1.271035e-17.]
[>
In fast_selxavg3bc (line 318)]
norm(inv(XtX),2)
= [14601308845709730.0]
Saving
X matrix to
/home/hector/SENS_MAPPING_BLOCK/sessions/HEC_035_1/bold/MPBDandefs_orig_lhrh_revd11.5_sm2.lh/Xtmp.mat
XCond
= 2.63784e+16 (normalized)
ERROR:
design is ill-conditioned
>>
------------------------------------------
ERROR:
fast_selxavg3bc() failed\n
Many
thanks in advance,
Martin