Untitled

The eig command will give just the eigenvalues if one output is given, or both

and

if two are given.

A = pi*ones(2,2);
lambda = eig(A)
lambda = 
                   0
   6.283185307179586

[V,D] = eig(A)
V = 
  -0.707106781186547   0.707106781186547
   0.707106781186547   0.707106781186547
D = 
                   0                   0
                   0   6.283185307179586

We can check the fact that this is an EVD.

norm( A - V*D/V )   % /V is like *inv(V)
ans = 
     8.881784197001252e-16

Even if the matrix is not diagonalizable, eig will run successfully, but the matrix

will not be invertible.

[V,D] = eig([1 1;0 1])
V = 
   1.000000000000000  -1.000000000000000
                   0   0.000000000000000
D = 
     1     0
     0     1
rankV = rank(V)
rankV = 
     1