Hi Dr. Taylor, sorry that I found another question w.r.t bmtxt file.
The Tortoise "DTI_DMC.bmtxt" has perfect correspondence with AFNI export "BMTXT.txt", both with 6 columns.
Assume that a particular row in DTI_DMC.bmtxt is: [a, b, c, d, e, f]
I found the correspondent row observed in AFNI export BMTXT.txt is: [a, d, f, b, -c, -e]
Given diagonal-first order (AFNI) is: Bxx, Byy, Bzz, Bxy, Bxz, Byz, while row-first order (Tortoise) is: Bxx, 2*Bxy, 2*Bxz, Byy, 2*Byz, Bzz, the above is confusing to me.
The switch in order suggests a conversion between 2 order systems. However, the minus sign (of c,e) and "2*" (of Bxy, Bxz, Byz) do not conform to the 2 different order systems (I would expect [a, d, f, b/2, c/2, e/2], not [a, d, f, b, -c, -e]; I'm wondering whether the minus sign is related to the flip-y?).
Could you please clarify this for me and guide me how to apply 1dDW_Grad_O_Mat correctly in this situation?
Thanks a lot, JoJo ~
