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:

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

History of AFNI updates  

April 06, 2022 09:56PM

This is interesting. I did a little bit of example testing and had an illuminating discussion with The Bob (with whom *all* discussions are illuminating) about this.

Can I ask what dataset you are using?

3dFWHMx is basically meant to be run on residuals---things that should be pretty deeply detrended already. This is because the predominant usage of this program is to estimate spatial distribution of noise in the data---and residuals are typically the approximation to noise that FMRI produces.

3dFWHMx's detrending is different than 3dDetrend's; as the help notes elsewhere, under the "-detrend .." option:
**N.B.: This is the same detrending as done in 3dDespike;
                using 2*q+3 basis functions for q > 0.
3dDespike uses trig functions to remove spikes/detrend (I think it might be something like a finite order approximation to Fourier expansion, with a bit of extra polynomial fitting).

Different detrending will affect 3dFWHMx results, but if you are inputting residuals, the differences should be pretty minimal (hence why I asked what you were inputting, above).

I'm not sure what the calfun error is. If you post the full output (along with input description), that might help.

Subject Author Posted

-detrend option in 3dFWHMx vs 3dDetrend

Zixun March 30, 2022 02:55AM

Re: -detrend option in 3dFWHMx vs 3dDetrend

ptaylor April 06, 2022 09:56PM

Re: -detrend option in 3dFWHMx vs 3dDetrend

Zixun May 06, 2022 07:23AM

Re: -detrend option in 3dFWHMx vs 3dDetrend

ptaylor May 10, 2022 10:41AM