Hello freesurfers,

Does anyone know the physical meaning of the "transform matrix" and the "quasinewton matrix" outputted during "EM Registration" of auto-recon2? For some odd reason, both of them are identity matrices (one's along the diagonal). I am almost certain that should not be the case.

Here is some context:

************************************************ Computing MAP estimate using 1658 samples... ************************************************

* dt = 5.00e-06, momentum=0.80, tol=1.00e-05*

* l_intensity = 1.0000*

* Aligning input volume to GCA...*

* Transform matrix 1.00000 0.00000 0.00000 0.00000; 0.00000 1.00000 0.00000 0.00000; 0.00000 0.00000 1.00000 0.00000; 0.00000 0.00000 0.00000 1.00000;*

* nsamples 1658 Quasinewton: input matrix*

* 1.00000 0.00000 0.00000 0.00000; 0.00000 1.00000 0.00000 0.00000; 0.00000 0.00000 1.00000 0.00000; 0.00000 0.00000 0.00000 1.00000;*

* THE SEARCH DIRECTION IS NOT A DESCENT DIRECTION IFLAG= -1 LINE SEARCH FAILED. SEE DOCUMENTATION OF ROUTINE MCSRCH ERROR RETURN OF LINE SEARCH: INFO= 0 POSSIBLE CAUSES: FUNCTION OR GRADIENT ARE INCORRECT OR INCORRECT TOLERANCESoutof QuasiNewtonEMA: 005: -log(p) = -0.0 tol 0.000010*

* Resulting transform:*

* 1.000 0.000 0.000 0.000; 0.000 1.000 0.000 0.000; 0.000 0.000 1.000 0.000; 0.000 0.000 0.000 1.000;*

* pass 1, spacing 8: log(p) = -4.8 (old=-5.1)*

* transform before final EM align:*

* 1.000 0.000 0.000 0.000; 0.000 1.000 0.000 0.000; 0.000 0.000 1.000 0.000; 0.000 0.000 0.000 1.000;*

Thank you and happy holidays!

- Mark