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Dear Paul, > I am processing DTI data using eddy, followed by fdt and bedpostx in FSL 6.0.0. FDT runs as expected but bedpostx gives the errors: > eig_sym(): failed to converge > Mat::operator(): index out of bounds > The images in eddy.nii.gz appear normal, at least there's no obvious corruption. The only odd thing is that the data type is changed from int16 to float32. I ran another data set successfully, and this also had float32 output from eddy, so I'm guessing this is normal. > I'm using autoptx to run everything, but am testing using bedpostx on its own too. I think bedpostx runs OK on the data before eddy. Am double-checking. > Can anybody suggest how I can get bedpostx to run on my eddy-corrected data? it is _possible_ that this is caused by (small) negative values in the eddy corrected images. Eddy uses spline interpolation in order to get optimal quality, but it also means one will end up with negative values in the vicinity of sharp edges in the images. Any processing that involves taking the log of the image data will fail, unless it has some strategy to deal with negative values. You can see if this is the problem by setting any negative values in your eddy corrected data to some very small positive value and see if that fixes the problem. Jesper > Thanks > Paul Wright > KCL > > ######################################################################## > > To unsubscribe from the FSL list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=FSL&A=1 ######################################################################## To unsubscribe from the FSL list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=FSL&A=1