Samsung Photosphere orientations.txt data
I've noticed that most elements are less than 1. Moreover the first 9 elements seem to be always less than 1. It looked like elements of a rotation matrix. So I grouped these elements into 3x3 matrix and it happened to be orthogonal, and it is in fact rotation matrix.
-0.28355762  0.95895493  7.3134253E-4
-0.19058217 -0.057101488 0.9800091
 0.9398263   0.2777497   0.19895127

If the phone is in landscape orientation and points to the North than the matrix is identity matrix:
 0.9999746    0.0067272037 0.0023434649
-0.0067065083 0.9999394   -0.008729676
-0.0024020493 0.008713738  0.9999592 

The last element in the row is the sum of all elements of the matrix. I don't know why it is added, because it doesn't seem to have any physical meaning, but I guess that it is some form of a checksum.