find_inv_G_fromA

This function computes the invariant matrices G1,G2,G3
starting from the A matrix computed via the function amat().
The resulting invariant matrices G1,G2,G3 satisfy
 M^T G_a M = G_a for a=1,2,3

0001 function [G1 G2 G3]=find_inv_G_fromA(A)
0002 %This function computes the invariant matrices G1,G2,G3
0003 %starting from the A matrix computed via the function amat().
0004 %The resulting invariant matrices G1,G2,G3 satisfy
0005 % M^T G_a M = G_a for a=1,2,3
0006 
0007 I1 = ...
0008 [1 0 0 0 0 0;...
0009  0 1 0 0 0 0;...
0010  0 0 0 0 0 0;...
0011  0 0 0 0 0 0;...
0012  0 0 0 0 0 0;...
0013  0 0 0 0 0 0];
0014 
0015 I2 = ...
0016 [0 0 0 0 0 0;...
0017  0 0 0 0 0 0;...
0018  0 0 1 0 0 0;...
0019  0 0 0 1 0 0;...
0020  0 0 0 0 0 0;...
0021  0 0 0 0 0 0];
0022 
0023 I3 = ...
0024 [0 0 0 0 0 0;...
0025  0 0 0 0 0 0;...
0026  0 0 0 0 0 0;...
0027  0 0 0 0 0 0;...
0028  0 0 0 0 1 0;...
0029  0 0 0 0 0 1];
0030 
0031 
0032 G1 = inv(A)'*I1*inv(A);
0033 G2 = inv(A)'*I2*inv(A);
0034 G3 = inv(A)'*I3*inv(A);