function X = rotx( theta ) % rotx spatial coordinate transform (X-axis rotation). % rotx(theta) calculates the coordinate transform matrix from A to B % coordinates for spatial motion vectors, where coordinate frame B is % rotated by an angle theta (radians) relative to frame A about their % common X axis. c = cos(theta); s = sin(theta); X = [ 1 0 0 0 0 0 ; 0 c s 0 0 0 ; 0 -s c 0 0 0 ; 0 0 0 1 0 0 ; 0 0 0 0 c s ; 0 0 0 0 -s c ];