Therefore, the Lane–Emden equation has the solution θ θ ( ξ ξ ) = 1 1 + ξ ξ 2 / 3 when n = 5 . This solution is finite in mass but infinite in radial extent, and therefore the complete polytrope does not represent a physical solution. Chandrasekhar believed for a long time that finding other solution for n = 5 "is complicated and involves elliptic integrals".