Legendre-polynomials

C++ functions which evaluate Legendre polynomials

P₀(x):
template <class T> T P0(const T& x);

P₁(x):
template <class T> T P1(const T& x);

P₂(x):
template <class T> T P2(const T& x);

P_n(x):
template <class T> T Pn(unsigned int n, const T& x);