Need help with a fortranroutine that calculates the associated Laguerre functionby d4n1el Tags: fortran, numerical analysis, qm calculation 

#1
Aug1011, 04:33 PM

P: 3

Hi!
Im trying to do some rather easy QMcalculations in Fortran. To do that i need a routine that calculates the generalized Laguerre polynomials. I just did the simplest implementation of the equation: [tex]L^l_n(x)=\sum_{k=0}^n\frac{(n+l)!(x^2)^k}{(nk)!k!}[/tex] I implemented this in the following way:
So my questions are: Do you see some obvious mistakes? Do you think there are possibilities for numerical errors? (In such a case, do you have any advices on improvments?) When i have been googling around, it looks like alot of the numerical implementations are using recursive relations. What are the pro's and con's for doing this kind of calculation in such a manner? 



#2
Aug1211, 06:42 AM

HW Helper
Thanks
P: 5,520

What is gamma? Is it an array, a function, a subroutine?




#3
Aug1211, 08:44 AM

Sci Advisor
P: 2,751

I just did the simplest implementation of the equation: [tex]L^l_n(x)=\sum_{k=0}^n\frac{(n+l)!(x^2)^k}{(nk)!k!}[/tex] I implemented this in the following way:
Where did the (l+k)! term come from? Why isn't "r" squared. 


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