'Returns the logdet of SDP matrix A.
For SDP matrix A, this is the sum of logs of eigenvalues of A
and is equivalent to the nuclear norm of the matrix logarithm of A.'

@Atom.numpy_numeric
def numeric(self, values):

    (sign, logdet) = LA.slogdet(values[0])
    if (sign == 1):
        return logdet
    else:
        return (- np.inf)
