I have a matrix , for instance, like this :
matrix[a_ ] := {{0, a}, {-a, 1}};
Eigenvalues[matrix[a]]
and this give the eigenvalues that depends on a
{1/2 (1 - Sqrt[1 - 4 a^2]), 1/2 (1 + Sqrt[1 - 4 a^2])}
If I plot this eigenvalues,
Plot[Eigenvalues[mat[a, b, q]], {a, -1 , 2}]
this just give me the real value. I would like to have the real part of the complex number too. How can I get the real part of the complex eigenvalue?