function X = xlt( r ) % xlt spatial coordinate transform (translation of origin). % xlt(r) calculates the coordinate transform matrix from A to B % coordinates for spatial motion vectors, in which frame B is translated by % an amount r (3D vector) relative to frame A. r can be a row or column % vector. X = [ 1 0 0 0 0 0 ; 0 1 0 0 0 0 ; 0 0 1 0 0 0 ; 0 r(3) -r(2) 1 0 0 ; -r(3) 0 r(1) 0 1 0 ; r(2) -r(1) 0 0 0 1 ];