"Laguerre function"

clear

L(x,n,m) = (n + m)! sum(k,0,n,(-x)^k / ((n - k)! (m + k)! k!))

check(L(x,1,0) == laguerre(x,1,0))
check(L(x,2,0) == laguerre(x,2,0))
check(L(x,2,1) == laguerre(x,2,1))
check(L(x,3,0) == laguerre(x,3,0))
check(L(x,3,1) == laguerre(x,3,1))
check(L(x,3,2) == laguerre(x,3,2))
