How to solve this matrix equation

Answer 1

[Daniel Vieira]

x=A\b

where A is the matrix and b is the left-hand vector. notice that, since this is not a square matrix, the solution is not exact, but a least-squares approximation.

Answer 2

[Les Beckham]

Since there are more equations than unknowns, there is no unique solution. A least-squares solution can be found using the \ operator, documented here: https://www.mathworks.com/help/matlab/ref/mldivide.html

A = [ 0.23 1.77 -2.57
      0.83 1.17 -3.94
      1.5  0.5  -3.46
      1.94 0.06 -1.37
      1.17 0.83  3.94
      0.06 1.94  1.37 ];
b = [48.8; 41.1; 39.8; 31.2; 46.8; 53.3];
sigma = A\b

sigma = 3×1

17.3243 26.6121 0.8502

A*sigma

ans = 6×1

48.9031 42.1657 36.3510 34.0412 45.7072 53.8317