calc_S_reduced

% Skew matrix with independent selected rows
 see PCV (7.120) ff

 Usage:
   [S,R] = calc_S_reduced(x)

   Ss - 2x3 skew matrix, reduced to independent rows
   Rm - 2x3 reduction matrix: Ss = Rm * S 

 Wolfgang Förstner 02/2010
 wfoerstn@uni-bonn.de 

 See also calc_S, calc_v_from_S

0001 %% Skew matrix with independent selected rows
0002 % see PCV (7.120) ff
0003 %
0004 % Usage:
0005 %   [S,R] = calc_S_reduced(x)
0006 %
0007 %   Ss - 2x3 skew matrix, reduced to independent rows
0008 %   Rm - 2x3 reduction matrix: Ss = Rm * S
0009 %
0010 % Wolfgang Förstner 02/2010
0011 % wfoerstn@uni-bonn.de
0012 %
0013 % See also calc_S, calc_v_from_S
0014 
0015 function [S , R] = calc_S_reduced(x)
0016 
0017 % select index with maximum |x|
0018 [~,i] = max(abs(x));
0019 
0020 % generate rselection matrix
0021 switch i
0022     case 1
0023         R = [0 1 0;0 0 1];
0024     case 2
0025         R = [1 0 0;0 0 1];
0026     case 3
0027         R = [1 0 0;0 1 0];
0028 end
0029 % generate selected matrix
0030 S = R *calc_S(x);
0031