eigenvalue problem



Hi,

If I define the following matrix:

x:matrix([1,0,%i],[0,2,1],[-%i,1,1]);

and attempt to solve the eigenvalues:

eigenvalues(x);

I get three values, which all seem to be imaginary. I suppose this can 
be seen by
applying float() on the roots as they all come up with imaginary parts.

If I construct the characteristic polynomial: -l^3 + 4l^2 - 3l - 1 = 0,
I seem to get the same result when solving for l with maxima.

Now, the problem is, of course, that the matrix x is Hermitian and the 
eigenvalues
should be real. If I use the generic formula for cubic equations and 
solve the characteristic
polynomial eq., I get real roots.

Any hints what maxima is thinking?


Jussi Eloranta
Department of chemistry and biochemistry
Cal State Northridge