Given the orientation matrix, for example: 0.284, 0.921, -0.265, -0.720, 0.388, 0.575, 0.633, 0.027, 0.773, and the angles of grain boundary in the XY plane (α= 166o) and in the XZ plane (β = 67o), how to obtain the index of the grain boundary plane.
The answer is: -0.562, 0.599, 0.570. This is an example from paper: Randle, V. (1995). Crystallographic characterization of planes in the scanning electron microscope. Materials characterization, 34(1), 29-34.
And in the attached file, I show details of my calculations: