AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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dmomi
March 04, 2022 09:06AM
Dear AFNI expert,

I am using the following command to bandpass filter my fMRI data 

3dBandpass -prefix filtered_func_data_clean_bandpassed.nii.gz -nodetrend 0.010000 0.120000 filtered_func_data_new.nii.gz


However, I notice that if I extract the FC matrix after 3dBandpass the eigenvalues are negative which should not be the case with Pearson Correlation. I've seen that this indeed doesn't happen if I skip the bandpass filter in my pipeline.
Of course, it is related with something that 3dBandpass is doing in the background

Would you mind provide me an insight why that?

Thanks

Dave
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Subject Author Posted

Negative eigenvalues after 3dBandpass

dmomi March 04, 2022 09:06AM

Re: Negative eigenvalues after 3dBandpass

ptaylor March 08, 2022 08:00PM

Re: Negative eigenvalues after 3dBandpass

dmomi March 09, 2022 10:27AM

Re: Negative eigenvalues after 3dBandpass

ptaylor March 09, 2022 02:26PM