Ask Your Question

A bug in Laguerre-L?

asked 2014-10-21 16:54:59 -0500

Peter Luschny gravatar image

updated 2014-10-22 06:02:02 -0500

laguerre(-1,1) returns 0 in Sage but returns exp(1) in Maple and Mathematica.

The docs say: "Return the Laguerre polynomial for integers n>−1."

Is this expected behaviour to return an innocent value instead of giving the user a warning?

Edit: I give an example how this behaviour can bite: Look at the Inverse Lah transform of 1,2,3,... which starts 1, -2, -1, 2, 17, 94, 487, ... This can be computed by


This expression gives for n=0 the expected value '1' and thus hides the fact that the formula is true only for n>0!

edit retag flag offensive close merge delete

1 answer

Sort by » oldest newest most voted

answered 2014-10-21 19:23:28 -0500

kcrisman gravatar image

Great point. Those orthogonal polynomials haven't had much TLC for a long time. I've opened for this.

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower


Asked: 2014-10-21 16:54:59 -0500

Seen: 36 times

Last updated: Oct 22 '14