Hi Doug,
I am trying to convert MNI to RAS. I know the formula to convert from RAS to MNI is:
MNI305RAS = TalXFM*Norig*inv(Torig)*[tkrR tkrA tkrS 1]'
In theory, I should just be able to just invert this, but I am having difficulties because TalXFM is a non-square matrix and therefore not invertible. In addition, I tried using the moore-penrose pseudoinverse of the matrix but the values obtained do not match those in tkmedit. Do you have a formula for going from MNI to RAS or any advice about how would go about doing this?
Thank you,
Jared