function X = Xroty( theta ) % Xroty spatial coordinate transform (Y-axis rotation). % Xroty(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 Y axis. c = cos(theta); s = sin(theta); X = [ c 0 -s 0 0 0 ; 0 1 0 0 0 0 ; s 0 c 0 0 0 ; 0 0 0 c 0 -s ; 0 0 0 0 1 0 ; 0 0 0 s 0 c ];