calc_Mq_comm

% Multiplication matrix for quaternions, commuted factors
 p q = calc_Mq_comm(q)*p, see PCV (8.46)

 Usage:
    M = calc_Mq_comm(q)

   q - double 4x1, quaternion

   M - double 4x4, Multiplication matrix for quaternions

 Wolfgang Förstner
 wfoerstn@uni-bonn.de 

 See also  calc_Mq, calc_R_from_opq_kraus, calc_r_phi_from_R, calc_Rot_ab,
 calc_Rot_q, calc_Rot_r, calc_Rot_rod, calc_Rot_rp,
 calc_opq_from_R_Kraus

0001 %% Multiplication matrix for quaternions, commuted factors
0002 % p q = calc_Mq_comm(q)*p, see PCV (8.46)
0003 %
0004 % Usage:
0005 %    M = calc_Mq_comm(q)
0006 %
0007 %   q - double 4x1, quaternion
0008 %
0009 %   M - double 4x4, Multiplication matrix for quaternions
0010 %
0011 % Wolfgang Förstner
0012 % wfoerstn@uni-bonn.de
0013 %
0014 % See also  calc_Mq, calc_R_from_opq_kraus, calc_r_phi_from_R, calc_Rot_ab,
0015 % calc_Rot_q, calc_Rot_r, calc_Rot_rod, calc_Rot_rp,
0016 % calc_opq_from_R_Kraus
0017 
0018 function M=calc_Mq_comm(q)
0019 
0020 a = q(1);
0021 b = q(2);
0022 c = q(3);
0023 d = q(4);
0024 M =[ a -b -c -d; ...
0025     b  a  d -c; ...
0026     c -d  a  b; ...
0027     d  c -b  a
0028     ];