I believe we had that topic a while ago.

I tried to import a transformation matrix from flirt into 3dWarp using the -fsl_matvec option.

That didn't work for me.

Looking at the transformation matrix from a simple shift example 3dWarpDrive gets me (re-arranging in rows):
1 0 0 7
0 1 0 5
0 0 1 3

and flirt gives me (ignoring line 4 from flirt matrix)
1 0 0 7
0 1 0 -5
0 0 1 -3

As I understand -fsl_matvec is supposed to fix that sign difference, but using that with 3dWarp doesn't work correctly for me, while manually changing that sign did.

Any insight please?

Thanks,
Wolfgang