def __getitem__(self, index):
if not isinstance(index, Expr):<EOL><INDENT>raise Exception("<STR_LIT>")<EOL><DEDENT>elif self.status == "<STR_LIT>":<EOL><INDENT>raise Exception("<STR_LIT>")<EOL><DEDENT>else:<EOL><INDENT>return get_xmat_value(index, self)<EOL><DEDENT>
Obtained the value for a polynomial in a solved relaxation.

        :param index: The polynomial.
        :type index: `sympy.core.exp.Expr`

        :returns: The value of the polynomial extracted from the solved SDP.
        :rtype: float