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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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Thanks Bob!
This information is invaluable.
The reason I asked is that
I just had a hunch from playing around with some synthetic gaussian spatial ACF images that the 3dFWHMx' s ACF 'a' parameter's upper limit is 0.9940 and hence the -acf option will overestimate the spatial correlation. I guess one should employ the "classic" method FWHM-estimate when the spatia
by
Gopi
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AFNI Message Board
Hi AFNI gurus
Can someone let me know the details of the algorithm used to fit the auto-correlation function in 3dFWHMx?
Specifically how was the equation ACF(r) = a * exp(-r*r/(2*b*b)) + (1-a)*exp(-r/c) fitted?
Did you use some kind of a non-linear data fitting algorithm? What were the upper and and lower bounds allowed on the ACF parameters "a", "b" and "c" ?
by
Gopi
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AFNI Message Board