[Eeglablist] NaN in AMICA

[Tyler Grummett]

Dear EEGLABers (particularly Jason Palmer)


Ive been using EEGLAB and AMICA for many years now and theres been an issue I've been meaning to ask about for a while now. Sometimes when I run an AMICA, the 'LL' and 'nd' in the final iteration are NaNs. For example (last couple lines of output):


...

 iter  3993 lrate =  0.0000004768 LL =   0.2151813642 nd =  0.0066193118, D =   0.11548E+01  0.11548E+01  ( 44.53 s, 198.0 h)
 iter  3994 lrate =  0.0000004768 LL =   0.2151813668 nd =  0.0066193124, D =   0.11548E+01  0.11548E+01  ( 44.42 s, 197.5 h)
 iter  3995 lrate =  0.0000004768 LL =   0.2151813695 nd =  0.0066193130, D =   0.11548E+01  0.11548E+01  ( 44.42 s, 197.5 h)
 iter  3996 lrate =  0.0000004768 LL =   0.2151813720 nd =  0.0066193133, D =   0.11548E+01  0.11548E+01  ( 44.56 s, 198.1 h)
 iter  3997 lrate =  0.0000004768 LL =   0.2151813746 nd =  0.0066193139, D =   0.11548E+01  0.11548E+01  ( 44.27 s, 196.8 h)
 iter  3998 lrate =  0.0000004768 LL =   0.2151813771 nd =  0.0066193143, D =   0.11548E+01  0.11548E+01  ( 44.55 s, 198.0 h)
 iter  3999 lrate =  0.0000004768 LL =   0.2151813797 nd =  0.0066193143, D =   0.11548E+01  0.11548E+01  ( 44.49 s, 197.7 h)
 iter  4000 lrate =  0.0000004768 LL =   0.2151813823 nd =  0.0066193152, D =   0.11548E+01  0.11548E+01  ( 44.05 s, 195.8 h)
 iter  4001 lrate =  0.0000004768 LL =   0.2151813824 nd =  0.0066193255, D =   0.11548E+01  0.11548E+01  ( 48.06 s, 213.6 h)
 iter  4002 lrate =  0.0000004768 LL =   0.2151813847 nd =  0.0066193309, D =   0.11548E+01  0.11548E+01  ( 44.39 s, 197.3 h)
 iter  4003 lrate =  0.0000004768 LL =   0.2151813871 nd =  0.0066193324, D =   0.11548E+01  0.11548E+01  ( 44.35 s, 197.1 h)
 iter  4004 lrate =  0.0000004768 LL =   0.2151813892 nd =  0.0066193335, D =   0.11548E+01  0.11548E+01  ( 44.49 s, 197.7 h)
 iter  4005 lrate =  0.0000004768 LL =   0.2151813914 nd =  0.0066193340, D =   0.11548E+01  0.11548E+01  ( 44.62 s, 198.2 h)
 iter  4006 lrate =  0.0000004768 LL =            NaN nd =           NaN, D =   0.11548E+01  0.11548E+01  ( 44.28 s, 196.7 h)
 Got NaN! Exiting ...
... done. Execution time: -10.23 h


Since first noticing this till now, I have code that checks the output for this issue and reruns the AMICA. A lot of the time it will eventually and properly end with the learning rate not decreasing by 1e-9 for five iterations (I think thats what it is). Ive checked the data, it seems fine.


I guess what I am asking is: "Is this an issue?" or am I incorrectly classifying it as an issue. If it is an issue, Im wondering why it doesnt reset itself.


Kind regards,

Tyler


*************************

Tyler Grummett ( BBSc, BSc(Hons I))
PhD Candidate
Brain Signals Laboratory
Multimodal Recording Facility
Flinders University Tonsley Building
Rm 4.17
Ext 19573
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